Hi mengler12
Go to Extensions -> Languages -> Overrides -> New - select the override for administrator section as img below
http://prntscr.com/ofx17q
Then add new value for DT_SPEAKER constant
http://prntscr.com/ofx1fl
http://prntscr.com/ofx1y5
Same thing to add front end new word value this time override for site and not administrator for string
DT_SPEAKERS
/language/en-GB/en-GB.com_dtregister.ini
Regards