Wish there was a easier/simple way to change the radio channels for the Zigbee in Home Assistant overall. Or a more complete step by step instructions in the documentation. I followed what was there but my channel went from 15 to 20 not the 25 that I wanted, using the YAML config file. Then trying to migrate it with the integration. Basically, all clear as mud. Very frustrating to say the least.
ZHA developers are working on it and puddly has just implemented an the need API in the underlying zigpy library that was lacking to make it happen → Implement an API to change channels by puddly · Pull Request #1190 · zigpy/zigpy · GitHub
Home Assistant core ZHA component and Home Assistant’s frontend UI implementations is still missing however sure that it will be prioritized next now that the underlying work is done.
Also note that there is not yet support for it in alla zigpy radio libraries and different radios / Zigbee stacks will handle it differently. So far it sounds as if the znp radio library for Texas Instruments radios will work best, at least so far:
PS: You should not really have the need to change the Zigbee channel unless your neighbours have stong WiFi that you can not change. Read and follow all of these tips regardless → Guide for Zigbee interference avoidance and network range/coverage optimization