A TRACON Controller reported they accepted a handoff from the adjacent facility of an aircraft that was below the Minimum Vectoring Altitude.

Narrative

I was instructing OJT on radar west combined with all radar sectors and coordinators. My CPC-IT trainee accepted a handoff from ZZZ Approach on Aircraft X. Aircraft X was at 4000MSL landing ZZZ. ZZZ Approach called to advise they were requesting the visual approach at ZZZ and I asked them to keep Aircraft X at 4000MSL. I believed Aircraft X was in a 3800 MVA and wanted to ensure they did not descend below that altitude; which ZZZ sometimes has them assigned. ZZZ did not hear what I said so my trainee called back and reiterated; to which ZZZ replied they were level at 4000. Shortly after Aircraft X checked in on our frequency I realized they were actually farther north than I thought and were inside of a 4200 MVA. I immediately instructed my trainee to climb them to 4200 to recover the separation. A few miles later Aircraft X reported the field in sight and cancelled IFR.I believe the main factor was my trainee's different radar scope settings than my own; making it more difficult for me to discern the MVA boundaries from airspace boundaries. OJTIs (On the Job Training Instructor) should always use extra vigilance when viewing their trainee's scopes that will have different setups than their own.