Unfortunately this is not going to be a easy change as far as I know. You will need to do a lot of customization, My suggestion would be to raise a Hi ticket to get the support from serviceNow.
Please mark the answer helpful and correct if it resolves the issue. Happy scripting
-Shantanu
found this link which has the steps and no scripting required, see if that works for you as well
Display of the request number under RITM in the My requests widget - response from snowuser yt
I was able to achieve using the steps shared in above link
Before: REQ shown
After: RITM shown instead of REQ
If my response helped please mark it correct and close the thread so that it benefits future readers.
