This could be normal, expected behavior in a file hosted from a server if the fields have global storage specified.
The values in global fields are unique to the user session and changes to their values are not retained. If that describes your fields and database, reply back and someone can share options for doing what you want that will retain those values for you.
I'm working on a stand-alone version--not connected to a server. But your suggestion about global fields made me realize I didn't have "use global fields" checked. Now that this option is checked, the text did not disappear after switching to another record. Thank you for your help!
Then the text isn't actually disappearing, it's just stored in a different record than what you pull up the next time.