Midland 850 jumping channels

I have just purchased a Midland 850 and set the channels to the other radios used on our campus setting. It works just fine, but one of them is picking up a transmission (from over 30 miles away!) on another channel and resetting to that channel. I do NOT have it set to scan. Any suggestions?

Thanks

Sue

Check to make sure the radio isn’t set to dual watch mode. (See the manual). It sounds like you are picking up a GMRS repeater.