To see all the channels in a team, click more channels beneath the list of channels you've favorited in that team.
You can also go to the team name, click More options > Manage team, and then open the Channels tab.
In the Channels tab, auto-favorited channels can be added or removed by team owners.
Tap Teams , then go to the team name and tap More options > View channels.
Tap Teams , then go to the team name and tap More options > Manage channels.
Tap Teams , go the end of the list of channels for your team, and choose All channels.