Merging layers makes the file super heavy

[merk5EB3]

Hi, hello to everybody, first of all sorry for my English. 

I'm new to Animate (version 20.0) and I'm facing some problem. I'm doing some small animations but I faced problems with the very first of them. I have my .FLA file and I need to update it, adding some details etc.

When I convert it to .GIF everything is fine, but when I make the .SWF or another video-type of saving, the layers/colors are wrong. I think this happens because (since I'm a new user and Idk how to do things properly) I made some layers with 50% of visibility or some tween weirdness and stuff like that. 

So, I suppose I need to modify a bit the layers/drawings etc, which is ok.

The problem is the fact the file has so many levels, way too many, which I need to merge to just few of them to work on, but every time I merge the layers, the file becomes heavy and heavier, from about 800MB (which is already a lot compared to longer video that I made later) to 4 GB and more, to a point where Animate crashes and I need to go back to the original 800MB(many layers) file and try another way to work. 

So, how to merge the layers keeping a lighter file? And how to keep a lighter file in general? 

I'm a noob so maybe the answer to solve this is very easy but I'm stuck on it since days now. Also I would not to do the same mistakes with the new files I should work on. 

Thank you very much. Merk. 

[kglad]

when you make a swf and you clicking file>publish?

[merk5EB3]

Thank you, I think I explained it badly. 

I want to edit the FLA file, merge the layers etc to create a lower number of layers to work on them to fix the error.

Cause when I make the file 'play' on the Animate window it works well, the same when I save/publish it as gif, then if I publish it as animation (SWF etc) it has wrong colours. 

If I have 50+ layers I'm not able to understand which one I need to modify to do the work done.

And when I merge the layers it's the FLA file that becomes heavy and make the software crash. 

[kglad]

50+ layers isn't a problem for animate.  the limit is 16,000 layers.

however, there's a much smaller number (somewhere ~10) of semi-transparent objects that can be over-laid without causing graphic anomalies and it doesn't matter whether they're in the same layer or not.