If in your project jenkins app is configured to slack to send notifications to a particular channel say “channel1” and now you want to move these notifications to “channel2”, you need to to the following steps.
Open jenkins and go to manage jenkins and then configure system.
Here go to Global Slack Notifier Settings where you can see the “channel1” in the channel or slack Id field, replace channel1 with the new channel “channel2”. This completes work on jenkins side.
Goto slack and then manage apps and select jenkins ci and then select configuration .Here you should see your old configuration, click edit and then replace channel1 in the post to channel field with new channel “channel2”. Save configuration. This completes the work on Slack side.
Now you are good to recieve notifications from jenkins in the new channel.