Overhead lights

I had an old lady stop me a few minutes ago in the parking lot and she can't get her overhead lights to go off in her Buick LeSabre. She stated the model was either a 90 or 92. Any help before I have to go find the fuse and disconnect them for the night? Thnx in advance

Not sure about Buicks but I know on Chryslers when you turn the dimmer switch to fully on the dome light come on.

Thanks all who replied!!!! There was a lever to control the brightness of the dash lights and I slid it back one notch and lights went out. The lady found her manual and I was able to find the switch then. Thnx again!!!!