At least 4 times the car would not start at all? I noticed the outside temperature was not showing and the clock had the wrong time?

We have the car listed above v6 LT. Over a year ago my husband replaced the battery. About 6 months later when we started the car, I noticed the outside temperature was not showing and the clock had the wrong time. We made a couple of stops and the temperature came back on. We drove a couple of hours and parked at a motel. I went to get my phone charger from the car, and I couldn’t get in. My husband got in and checked battery connections and all were good. Tried car and it started. We took to a Chevrolet dealership, and they said everything looked okay. Several times a week and sometimes in a day when I start the car, the radio is on a different channel and the clock is wrong. Several times I got messages to roll down driver's window and roll up again. At least 4 times the car would not start at all. Twice it was jump started. The other times we let the car sit and then it will start. My husband replaced the battery again and all was well for several weeks. Then I got the message to roll down driver's window again and car has started to do the same thing so far it has not refused to start but radio station is changed, and clock is wrong. Our Chevrolet dealership has had the car for a total of three weeks and could find nothing.