2. Try "search and replace everywhere" to fix the media links. Type Ctrl-H to bring up the Search and Replace dialog window. In the first dropdown, select "Multimedia filenames." Search for "C:\Users\user\Documents\Documents\Ancestry Ehlman-Feltel_media" (your old path name) and Replace with your new path name (including your new user name). This will point all the old computer links to the new computer location.
Thanks so much for your response. I followed your instructions in point 2 and RootsMagic can now find the Ancestry files. I will have to do more to reorganize other media and figure out how exactly I want to do that but this was a great first step. I will reflect on your points 1 and 3 and see which way I want to go. Thanks for such clear instructions and your ideas about media storage.