It sounds as though "Save Password in Credentials Manager"(/Keychain) has been ticked in the opening login dialogue in FM15. (although I thought that it would rember this across versions?!!)
To revert this. press Shift when opening the file if windows or the Option key if OS.
You will then get your login in dialogue back and make sure not to check the 'Save Password' option.
Thanks so much for responding. Holding down the shift key certainly worked to get me the opening window. I couldn't find a "save password" on that window, but did check the file options while the file was opened in FileMaker 15 advanced.. There was no instruction to save the password in credential manager. Figure below. Am I missing something?
No, your not missing anything:
Because 'Allow Credential Manager" is not set in File Options, then the 'Save Password in Credentials Manager' will not be shown as an option on the login dialogue.
Is all now working as should be, or when you open the file in FM15 (without pressing shift) does it still auto login? If ti does, then it may also be worthwhile checking that there is no active 'Guest' account in File>Manage>Security or any other account without a password set.
Alas, no. I suppose I could try to update the server to FileMaker 15, but I'm a little leery to do that since I was testing the FileMaker 15 advanced on my own machine to see how it would respond before installing it on machines of my clients. If I updated the server, and everybody was seeing the wrong layouts and such, I'd have a real sticky wicket. If you have any other ideas, I'd appreciate it, but otherwise thanks so much for the help.
Found the problem. There was a institutional network account activated on one of my files that recognized my computer and was granting access through that account. I inactivated that second account and the login window reappeared. However, what is still not clear is why the same settings produced a login window in FileMaker 14 advanced, but not in FileMaker 15 advanced when the server is running FileMaker 14 server software. I wonder if FileMaker 15 handles logins differently than FileMaker 14.