Hello and welcome.
The Nav screen only offers the map screen, on or off, and one of the optional screens such as audio, climate, etc., which only show temporarily and then revert to the map screen.
Did you purchase the car from the Lexus dealer Certified Previously Owned? If so, then all the appropriate service should have been done. If not, and I bought it privately or from a used car lot, I would take it in and have it checked out. That's just me.
I love my 350 and You should have many years of driving luxury,
Paul
you can change a setting to have one of the optional screens (audio, climate, phone, etc.) stay there and not revert to the map..I know that cause I did not want the display to keep going back to the map, so I looked into it..usually leave mine on audio
How did you do it? thanks again.