How do I manage the wifi channels on my Deco M3(3pack) and seperate 2.4g with 5g??? It seems the units choose all this automatically and I DO NOT like it. I want to control what channel my devices use

Hello I have bought the deco m4 set of 3. So far it's working good. Only problem is when i use the dual band feature it always connects to the 2.4g band and my speed is really slow. When i look at the