AC1750 Channel Selection and Signal Quality

I have a C6300 Wifi cable modem router that I cannot seem to obtain a quality signal with and need assistance. The singal strength seems to be good with MOST of my devices and the connection speed with my direct connection devices are flawless. However, when it comes to getting calls with Skype for Business in a wireless connection, my expereince drops significantly. There has got to be something I can to to enhance my signal so I can take calls wile on a wireless network. And to make matters worse, I am in an apartment complex so there are a fair share of devices surrounding me. I attempted to change my channel on the 5GHz side to be on a channel that has the least congestion, but the channel does not seem to stick. What am I missing? Is there any sugesstions in improving my quality and speed of my Wifi connection? I have tried different DNS servers like Google and CloudFlare, but they seemed to have slowed my connection rather than make it faster. The thing that does not make sense is that the admin page does not show a channel for GHz and even my NetSpot application shows my 5GHz being 2.4GHz, I do not get it.