After todays upgrading when users open chat they found themselves evertitime on that tab where can choose private channels.
They are furious now because they have to everytime change back to tab of public channels and then choose wanted channel instead of old system where chat opened to last used channel.
They want old style back. And I agree them 
Understood. We’re on it, @Jagster !
We intend to update this so that users go to Channels by default, and only land on the DMs tab when there is unread activity there.
As Lindsey said, we’re ironing out some things still.
However:
Chat still opens on the last visited page when you switch between forum-chat. So as long as a user doesn’t click the chat-icon while already in chat (which will bring you indeed back to the DM tab), they should stay within the confines of public channels.
Maybe tell them that to appease them for now, while waiting for the better fix 
That is not an issue, but good to know — I can use it to make my jumps a bit smoother
The issue is when they leave chat and forum by closing window/tab/browser or using (back to) Forum, and later opens chat again they are finding thmeselves browsing list of private chats insteaf of latest used chat channel or first one with unread messages.
And I would bet that most of forums in the world aren’t using so many channels that showing any kind chatlist would be beneficial. Including B2B-side where 1:1 chats can be more common than free-for-all bubbling channels, but even then should put a customer/user directly to channel (unless there is need to ask from customer what kind chat help he/she/it needs, that’s one scenario in deed).
Another default setting to adjust? There is quite many already, though.
We’ve updated mobile chat to default to the Channels tab — @Jagster can you let us know if you notice any other opportunities for improvement here?