The TG number and text tag are always shown on the display. If you would like to see the UID, who is transmitting, you press function button and then 9 to toggle the UID mode on and off.
If you want to change the text tag for a TG or UID then you append that system to a favorite list in Sentinel and then edit it.
If you only scan from database and not favorites then you'll have to edit the file in the SD cards HPDB folder that corresponds to the state you're in.
The UID number will show if it has no text tag but will only show the text and no number if it has a text tag programmed. You can add the number in the text tag but there's only a limited number of characters that can be displayed.
/Ubbe