Filemaker global database fields are unique to each user and that can be a problem if you want to share your Filemaker Pro database with Filemaker Go clients via your network. Basically, if I update a global field on my MacBook via Filemaker Pro, those updates are not reflected in when I then access that database via Filemaker Go.
The way around that — or at least one way around that — is not to use global database fields at all. What you can do instead is to set up a table with one record in it and use the fields in that table as pseudo-globals. It's probably easiest to use a serial number for the ID record rather than a GUID in this instance, so the one and only record in this table with have the serial number 1.
Then in any table that needs to reference the globals table, you just set up a number field that always contains 1.
Then you join those two tables and access your pseudo-globals via that relationship.
Filemaker uses the term global in a strange way in my opinion because I'd assume that meant they were the same everywhere, which is what I interpret as the meaning of the word global. Maybe there's scope for another category of database field for truly global fields.