You can change the way the Referencing works by going to Settings
Within Settings - select Reference generator
You can edit or change the reference to suit.
I.e Property prefix is currently
P%04d
P = prefix
04d = number of places
This will result in
P0001
You can change the Prefix by selecting edit next the reference you would like to change and simply replace the letter "P" with something more suitable to your requirements.
This will now generate the property reference to display as:
MP0001