Cant Hear Dialogue Over the Background Sound. I have a Yamaha HTR 5740 which I use for Home

Question

I have a Yamaha HTR 5740 which I use for Home Theatre. Often times, I have a hard time hearing the spoken dialogue coming from the center front speaker over the background coming through the other four speakers. I have misplaced my manual and this device overwhelms me with all its buttons. Can anyone tell me how I can fix this? I hear better with my TV speaker turned up than I do from my surround sound system which I paid a lot of money for. Thank You.I have a Yamaha HTR 5740 which I use for Home Theatre. Often times, I have a hard time hearing the spoken dialogue coming from the center front speaker over the background coming through the other four