When cropping in a "decent" photo editing program, the parts that are cropped off are discarded, and a new file is saved. The parts removed won't come back (even if you want them to).

In some programs it appears that when you "crop" an image, the removed parts are only "masked" so that they don't show in that program. If you subsequently move the image to a new program the "mask" may or may not go with it. Since I know virtually nothing about Picasso, I can't speculate whether it might have an unusual behavior of this kind.

The most common cause for images "reverting back" to a prior condition though is probably "mis-saving." This is a very common problem with programs that "automatically catalog and index" everything you do, where the default location for saves is some bizarre place you'd never think of looking for them, rather than back to the folder from which the image was opened. When you retrieve the image for another use, you go where you think you put it and get another image - or another version of the same image, while the one you think you're getting is where the program decided to put it because "it knows you're too stupid to do it right" so it has its own way with your stuff. (I have my own opinions about who's stupid in this kind of case, but the program designers continue to ignore me as the market is richer if they concentrate on selling to people who really are a little less than competent.)

Some websites where you post pictures also always save your original, but display a "reduced image" that's modified to fit their idea of appropriate size and resolution. If you edit the posted/displayed version on the site, it probably does not change the "original upload" and in some cases if you "save" the image back from the site you may get the last edited and displayed image, or you may get the original uploaded "full size" version. Some sites let you pick which you want, but even then knowing which one you've asked for can be "obscurely indicated."

With so many people making decisions for you, without telling what they're doing, it's difficult to avoid occasional frustrations, and shouldn't be an embarrassment to you; although cursing is still permitted while cursoring (depending on present company at the time, of course).

John