So if I have a lot of small graphics it would be better to have more atlases smaller sized than 2 big ones (2048x2048)?
Atlases are there for reason. If more atlases would be better than one, then you would not need atlases because your sprites are like small individual atlases... Generally speaking less atlases providing better memory footprints and rendering performance. But you also do not want to use too big atlases with unused spaces. Those would just occupy space in graphics memory and you will never use them. So for example you have two atlases, the first is full with small sprites and the second only have few of them, then the second one is just wasting memory on your graphics card. So you either increase the size of the first to fit everything in making sure it is not too big so that there will be not much of slack space, or you decrease the size of the second one to small enough to eliminate waste space. Other consideration is that you generally want to keep animation sequences in a single atlas - it is because of how graphics card handling these atlases, you do not want context changes too much. I am not sure how BuildBox automatic atlas generation algorithm works but I believe it tries to keep them in one place. If it does not happen you may can play with the sizes in a way that big sprites like background images and large menu decorations will only fit on the second atlas, while the first holds smaller ones only.
That i did, i have 2 atlases one full and another 5 images, so i increase the size of first and the game load ok . This is the reaseon i ask here, sould be better to make 2 sprites with the same images ?
What about the fonts. I'm not in front of my computer right now but I know that I have an atlas for each font. In my game this is equal to 7. All of them have a lot of free space. Is there a way to change the size of them as well? Update: I did an own thread for this question as it would be off topic in this one. https://www.buildbox.com/forum/index.php?threads/should-i-adjust-the-font-atlas-canvas.7690/
Generally speaking less atlases is better. Older devices can't load atlases larger than 2048x2048. Also, it takes four 2048x2048 atlases to equal one 4096x4096 atlas.