backing up issues

It now seems that my laptop and my Mac back up my files in different locations. I had thought they were all sent to the same dropbox folder. If I tell my laptop to back up the files to the same dropbox folder as the Mac, will that cause any problems?

Also is there an easy way for me to find out where my Scrivener documents are stored?

Long story short, I lost about 1/4 of my work in progress, and tried to restore it. Nothing worked, so now I’m very uptight about where to back up the documents.

I have Scrivener 3.