Lock changes after first record was made

[Atlas]

Hi team,

I have a USERNAME column with an app formula that gets the user name from a table. So when users fill the form for the first time they don’t need to select a name. But here is the problem, I made an action button to change specific columns, whenever another user uses the action button the user column value changes also.

How can I prevent changes in this column? Is there any way to lock the USERNAME column after the first record was saved?

Thank you.

[Steve]

Move your App formula expression to Initial value instead, the set Editable? to the expression, FALSE.

[Atlas]

Thanks Steve