@GoldenG 

Deco Mesh systems are different from the traditional router systems you are used to.  They utilize a more simplified and efficient approach to network management by letting the system, not the user do all of the work.  The system will determine based on several factors what channel and channel width are used.  It will also decide which band a device on the network used based on bandwidth needs and device capabilities.  This is all summed up in the Adaptive Routing Technology or ART.  We understand that at times when the system does the periodic check that network channel conditions may be very different than when you are actually using them so we have added in most systems a Network Optimize button that performs this check on demand.  

  @Carl The OP asked how to change the channel, not an explanation of why he cannot. It's nice that the system thinks it knows the best channel, and that is can choose the channel, but there is no reason to block that capability from the user. My Deco has chosen THE channel that is being used by almost all routers within range, and I can not change it. Clearly the OP's Deco is not using the best channel, and mine is using the worst possible channel. The software should allow the user to override the systems choice is the user wants to.  We own the products, not TP-link.

Regards.

  @HHaas 

The OP was talking about being on a congested channel and not being able to choose an unused one.  Then asked for suggestions.  My response was a detailed explanation of why they were able to choose to manually choose a channel but also that they should have a network optimization button that they can force the system to scan and assign an appropriate channel at the time of use.  If you would like to see future enhancements you can always leave a suggestion here.  If it is something that can be done then the team will evaluate its possible inclusion in a future update. 

There is no button on the web interface or the app for "Network Optimize".

I am running into the same problem.  I NEED to change the channel on this thing!