How do I restore all my layers when I restart krita? I save as png before I close it but the next day when I open the file I only have one layer. Where have all the others gone? How would I avoid this in the future too?

PNG does not support layers. The current master branch warns when you save an image with layers to png, but I doubt that people will actually notice that warning. Save your work ALWAYS in the native format of the application you're using. For Krita, that's kra.

Oh right, thanks! It's all very new to me and I heard somewhere you should save your work as png to get better resolution so I thought you were meant to do that always. I guess that is not how it is.

What you probably heard is that you should use PNG in preference to JPG. Apart from the fact that JPG also doesn't save layers, the difference is not one of resolution, the pixel count will remain the same, but of quality: JPG is lossy, i.e., it makes smaller files by not saving your pixels exactly as they are.

The rule of thumb is:

* always save your work in the native file format of your application (KRA for Krita, XCF for Gimp, PSD for Photoshop)
* when working with more than one application on the same image, save the best one they all support, often ORA or PSD or TIFF
* when exporting for the web, save as PNG

Thanks. I think that was what they were saying but I got confused and all the acronyms, initials, and abbreviations got jumbled in my head. I've written what you've said down so hopefully that will help me remember and I will also remember to look at it if I need to know again.