Something about that question is not quite right.
Is this login something that is supposed to last for the lifetime of the Access session? If the username is in a table, is it alone? Or are there other user records? The trick is knowing which record you want when that "other form" gets involved.
One way that some folks (including me) do this is to have a general module with some support routines that look up your username and validated it against the table of valid usernames. If the general module has a public string variable set aside for the purpose, you can store the login ID in that string and then other forms can reference it, since a public variable in a general module is about as close as you can get to something being global to the application as a whole.
In my current process, when the user opens the database, they are presented with a login screen, from which they select their name. This login determines which menu they will see while using the database. The USERID is a shortened version of their name (firstinitiallastname).
In one of my forms, (Trans Est), I want to automatically populate a field showing the person that created the Estimate.
I assume this USerID is stored someplace in the database, I just do not know where.
Before realizing the above possibility, I added a field (LoginID) to a table (tblImagePath) used in the login screen. I have successfully written the ID to the table. I can't figure out how to reference this field from my Estimate Form.
Either method would work.