Most often a User field cannot be edited due to its Read Only field type. To make a User field editable the field type must be changed from Read Only to Text Box / Default in the Data Screen Configuration window.
Open the Data Screen Configuration
- Open Utilities > Setup > Database
- Open Data Layout: Define
Data Screen Configuration
Select a User field
1. Select the Data drop-list and choose a User field
The Read Only field type is selected
Change the field type from Read Only to Text Box
1. Uncheck Read Only and check Text Box / Default
The Text Box / Default field type is selected
2. Click Save then Close