Click on SALES CHANNELS in the menu on the left

In the upper right corner, click on the GEAR icon of the sales channel you want to adjust

Then click on EVENTS and TICKETS

Click on the gray SHOWING EVENT

Choose the event (that the tickets are linked to) that you want to add and Click the orange SAVE button.

Click on the X/X TICKETS LINKED button and check the tickets you want to link to your sales channel

Click on the orange SAVE button