I can't change the opacity of individual frames

[PhoenicianPrincess88]

I"m trying to change each frame's opacity so that certain layers gradually get more and more transparent as the animation plays. But whenever I change the tranparency of, say, frame 434, frames 1-433 change as well, as well as all the frames after 434. I want it to get slightly more see-through until I reach the last frame, at 475. I tried copying and pasting a frame and then editing the copied one but that doesn't work either. :(

[DarrenT]

How did you change the opacity?

To change the opacity over time you have to use the Transparency node and change the animatable value. Make sure you're in any other mode than Constant (in the Animation section of the Preferences).

[Jane Eyre]

Are you using the opacity slider in the column header? That will always apply to the entire column/layer. As Darren suggested, you are better off using an FX node.