I don't think it deletes it. Unless you close it, then it asks if you want to save the changes if any. I think it will stack several songs with the latest one open on top. But, I rarely work in that manner. I like to save and close things before opening the next project.... not quite obsessive compulsive, but, I don't want anything to go wrong with an underlying project..... best to save and close before opening the next.... just to be sure. I've had too many complete losses through dumb mistakes in the past.

When you close a project you're working on, always click SAVE. Be sure to choose save as that first time and select the location and name..... From that point on, your file should open to the point it was at when you closed it. I always use the document window to write the words for my songs.... and when I reopen the file the next day, the document window pops right up if I had it open when I saved it.

You can find my music at:
www.herbhartley.com
Add nothing that adds nothing to the music.
You can make excuses or you can make progress but not both.

The magic you are looking for is in the work you are avoiding.