if since the recent patch you are having an issue with all channels showing again every time you log in, I found a workaround using the Prat addon https://www.curseforge.com/wow/addons/prat-3-0
Install the Prat addon, setup your chat as you like it then go to Options>Addons>Prat>Extra Stuff>Memory
Click Save Settings and tick Load Settings Automatically
(for alts set them all to the same profile e.g. default)
Note: when logging in it takes a couple of seconds for the settings to load so you will get some initial spam but then its fine