you for reaching out on the community and telling us about your issue. I do
apologize for the issue you're having. It sounds like the mobile sync keeps turning on after you turn it off. Is this correct? When does this turn it turn on? Does it do it after you re open the program? How are you turning it off as well? You can turn it off by going across the top to edit > preferences > mobile & web > sync off. Another option would be trying to also deselect all the accounts in the account selection area as well.
Once you get a chance let us know a bit more and we'll see what we can try next if you're still having issues.