When changing already saved data, Good Clinical Practice (GCP) requires you to indicate a reason why a field's value is changed (after an initial value was already set).
Enable GCP features
To enable this feature, under Study Settings, in the GCP section, select Yes:
Enabling GCP means that any time a user attempts to change previously entered data in a record, they will need to add a reason for change in order to save the new value. The user has 30 seconds after the entering of the data to amend or change the value without being required to provide a reason, after this any further amendments must be justified in the dialog window. The reason for change will not be prompted if the data is being entered for the first time, and the 30 second time allowance resets when each change is made.
Add a reason for change
For example, in a record you realise that you have checked the wrong box in a checkbox field and you want to change this. If you attempt to select a new box, you will be prompted to add a reason: