Alright so 2 things to consider (side note I'm not expert, but I've used VAM enough so far to tell you what follows):
1) When you use a Scene that someone made, containing any number of Atoms (male, female, 2 males, 2 females, whatever the combo may be) that happen to interact / collide with each other (so yeah, a Sex scene for example, or even just a scene where there's any sort of physical interaction that requires body parts to be placed in a specific way between the two Atoms) you must know that - the author who made that Scene - made it with 2 (or more) specific Atoms with specific physical characteristics to them.
So, that means that the Atoms' Scaling, Heights, Body part lengths (legs especially, but also arms length, and a few others) AND in the case of the Male / Futa the size / length of the Penis... ALL of them (and perhaps a few other things I'm not thinking of right now) are the overall physical Atom 'Values' that the Author made the Scene for. Or, well, in other words the Scene you're using was made for THOSE Atoms specifically.
Alright, so if you then want to bring in a new 'Look' (basically, replacing the Atom with a new one by changing the Look) then a load of physical values may (or may not, if you're lucky) change suddenly. The new Atom ('Look') you want to use might have a different Scale (say... could well be 0.990, instead of the usual default of 1.000), or a different Height (or the legs are slightly shorter, or longer). Not to mention that in the case of the Penis size maybe that also changed.
And that ultimately does explain about 90%+ of all the "Miss-alignment" issues that people report (including myself, when I started using VAM believe me... I ran into that like a Nascar at full speed into a wall). The reason why I explained all of that beforehand is to provide you with a clearer picture as to the sheer NUMBER of things that you might then have to manually Re-Adjust yourself in a Scene in order for the Penis (if at least that one) to align properly with the Atom it should interact with (that's not talking about other types of interactions like Blowjobs, or Handjobs, or Footjobs, or even just hands caressing or massaging in thin air instead of going where it's supposed to).
SO... with all this being said...
How CAN you improve the situation in a Scene when you change Looks?
Well, first you can use the DiviningRod Plugin (this Plugin is added to the Male / Futa Atom's plugins tab, not as a Scene or Session plugin):
Add plugin to any male to turn his rod into something that can find wet places ;) Will automatically align penis to nearest vagina or mouth of any other person atom. Anus and hands can also be enabled, but might need some individual parameter...
hub.virtamate.com
It DOES help, but it's not a miracle plugin. It won't make the Male / Futa Atom bend legs or back bones to compensate the actual positioning required for the Penis + Vagina (or Anus) to align. It will only play around with the actual Penis' own bones (or 'nodes') and rotate those in order to align. But if your Male Atom for example is simply too tall, if the scale is off by too much, if the legs are too long, etc... then YOU have to go in the Male Morphs tab and spend time there figuring out which things you can change in order to improve the situation.
A good, albeit time-consuming way to do that is first to NOT change the original Male Atom in the Scene, and simply look at all the important Values of that Atom first. Take pictures (which will appear in your VAM directory) or write down notes but basically check that Atom's Scaling, first (default is usually 1.000, but sometimes Authors need or want to make them smaller or larger so they just change the Scaling and nothing else), then go in the Atom's Male Morphs and search individually for specific Morphs like Height, check what the number of the value says, then check for Legs (length), Arms if necessary (example would be a Scene where the Male is suppose to be caressing the Female breasts, but if you change Looks suddenly the Male is caressing nothing, or the wrong thing). Take those notes or save pictures of the Morphs and so on and THEN apply those values to the new Look. Then combine all of that with the DiviningRod Plugin and you should be good to go.
However, it's not all over, yet. There's still the case of the Female Atom, too. If BOTH Atoms in the Scene are changed, then obviously you multiply all of what I typed above by two and you need to do the same for the Female Atom. For the Females sometimes even if things ARE aligned the Penis won't go in or 'pulls out' on its own, that's because then you'd have Colliders-related problems (not same values are the original ones that the Author of the Scene worked with). Which means you'd need to use the Colliders Plugin and fiddle around with those settings for the Female vagina to have proper Collider values in order to 'accommodate' the size of the new Atom's Penis (if you did change the Look and the new Look's Atom's penis is completely different). And, by the way, the Collider Plugin can also be used for Males (for adjusting Colliders for the Male's penis, too).
Alright... NOW... moving to the next main point...
2) Changing Looks...
Basically, let's say you find a new Look here you like on the Hub. It's a Scene, the 'Look' is the Atom herself (let's use a Female as an example).
So you download the VAR Scene (containing the girl you like and you'd want to use in other Scenes). That Var file is now in your AddonsPackages folder. Then you start up VAM and browse your Scenes and find that one new Scene you just downloaded (search by its name, or the Author's name and you might find it right away). Load that Scene.
When the Scene is loaded you click on the girl in Edit mode and you should be selecting one of her nodes (any one of them, doesn't matter). Then Select Root and all your options appear on the left side panel. Or, alternatively you can click the arrow on the User Interface (when in Edit mode), which is called 'Select', then choose the Atom in the Scene, normally named 'Person' (that's default but sometimes it's Person#1, Person#2, or sometimes it's a specific actual character name), then choose 'Control' in the new list of options appearing on the right side of the panel (which will then send you to the 'Root' options of that Atom from where you edit everything).
Now that you're there, you go in the Appearance Presets tab, and type in a name in the blank name space and create a new file save (well, a Look Preset basically). Good, now you've saved the girl's 'Look' (along with all her physical characteristics, like Morphs, scaling, textures, etc).
THEN... load the Scene you want to use that girl (or male) Atom in, where you would replace the existing Atom with the new Look.
Same process as above on the original Atom of the Scene. You Select the Atom you want to replace the Look of. You go in that Atom's Appearance Presets tab, then from there you to Select Existing (top left of that Appearance Presets tab window) and then you browse to your girl Preset you saved earlier. That's it, you load that Girl preset and it should automatically 'replace' the Atom with that girl for that Scene you're in.
And from there... you then re-adjust anything that needs to be adjusted.
Now, last thing...
If you change an Atom's Look DURING an animation, it can cause issues. Especially related to body collisions. So I recommend that you Pause the ongoing Animation (in Edit mode, it's the 'Freeze Motion / Sound checkbox) and then you do your Looks changes, and then you resume the animation. Or, alternatively, if you don't want to pause the Animation for whatever reason, you can always temporarily disable the soft body physics of the Atom that may be causing issues, for example, you can go in a Female Atom's F Glutes Physics tab and uncheck the 'Soft Physics Enabled' checkbox there which will temporarily alleviate a lot of potential problems like physics "explosions" when Morphs values and Colliders aren't adjusted.
So... yeah, long post but sort of necessary, there's a lot to consider.
In short, there's no "automation" processes in VAM to ensure perfect character interactions when changing Looks in a Scene that was done by an Author using his/her own sets of Atoms and other characteristics without the prediction (on the Author's part) that VAM users might want to change those things in the Scene. Now, SOME authors around DO actually create ways in their Scenes to create some sort of 'leeway' room to allow for some Looks-related changes without creating too many problems; but they're far and few. The majority of pre-made Scenes were made with specific Atoms in mind, for their own respective values and characteristics and it's up to the VAM user to take time to adjust everything on a Per-Scene basis and save those Scenes as a new one when those changes are done in order to not have to do those changes every time they load the original Scene.
Hope it all helps (sorry if you happened to know most of this but I prefer to go in more details just in case other people around would read this thread, it might help them too).
