Samsung PM-A840

so i've had this phone for about two months now, how do i get custom ringtones? ive looked, and the only ringtones i seem to be able to get are the ones already on the phone and the ones i buy online... can i somehow set the voice memos as ringtones? in the description it said it had custom ringtones.. buttt... cant find it. anyone wanna helpp?? thankss.