On_Select userexit in each menu/button-area or On_Event userexit in each state of the user interface.
The userexit creates an input mask, in which the current user first has to enter his old password for an authorization check. After DataView has checked this entry, he can enter a new password. After DataView has been restarted next time, the user can only use the new password to access the data of your application.
Example:
In DataView itself the userexit creates the input mask, when you select the Password button within the toolbar.