The channels that are marked as Favorite go to the top of their channel branch and have a star mark in their channel icon. Use the Show Favorite Channels filter button to display only channels marked as Favorite channels in your channel tree.
To mark a channel as Favorite, follow these steps:
Hover your cursor over the channel name in the channel tree on the left;
Click the 3-dot button that appears to the right of the channel name;
Select Mark as Favorite.
The channel is marked as Favorite!
If a channel marked as favorite is created under a Workspace, it's shown at the top of the channel tree. If a channel marked as favorite is created under a folder, it's displayed above all channels in this folder.
You can view all the channels marked as favorite using "Show favorite channels filter".