If global field values in a shared file situation are only saved on the host computer, how do I save a global field value when the file is being hosted by FM Server? Thanks.

Create a single-record Preferences table and store the value in there. This prefs table uses normal fields, not globals.

If you host the file localy, enter your global value, then open it on the server It should stick as the default. (I don't suggest doing this If there is ever going to be a reason to change what the defualt value is, it's a real pain to have a global field for a year always default to 1999, they do not survive a recovery process) The user can still change the value from the defualt but It only changes for them.