How do I change animations between frames without affecting the object in the whole animation?

[DragonClaw0123]

Basically I'm having some glasses come down. And on the far side of the face I need to erase the frame so it looks like it's behind the nose/face. But, when I do this and erase, it affects every layer. I'm using the tween option. How do I only affect the object I'm working on. I need to erase around the last 6 out of 30 frames differently. 

[c.pfaffenbichler]

Could you please post a screenshot with the pertinent Panels (Layers, Timeline, Options Bar, …) visible? 

Would an unlinked Layer Mask work?

Alternatively a separate Layer of the nose atop the glasses-Layer might be another option. 

[DragonClaw0123]

A later mask would be hard because the glasses need to go on the other side but only part of it

The SS below is my intended result.

The one below is how it's affecting prior layers even though I only erased on the last frame

[c.pfaffenbichler]

That is completely as expected and intended in Frame animation. 

I don’t understand why a Layer Mask should not work, can you explain? 

[DragonClaw0123]

To be fair I'm not really that experienced in them enough to know. I thought it might at first but I just don't see how it would now.

[c.pfaffenbichler]

The Layer Mask is not the ideal option anyway, but see the gif below: 

[c.pfaffenbichler]

Also: For moving and transforming a Layer (ideally a Smart Object naturally) Timeline Animation might offer more options. 

But if you are serious about animation you may want to look into more specialized applications, because Photoshop’s capabilities in this regard are limited.