It is not possible to switch to a different Instagram account from within the tab. You need to uninstall the app, install it again and log into the appropriate Instagram account.
You need to:
- Remove the app (click here to see the steps you need to follow)
- Add back the app (click here to see the steps you need to follow)
IMPORTANT: Uninstalling & reinstalling the app will not impact your subscription to a Premium plan. But all the customization settings will be lost and all the hashtag feeds previously created will be deleted. You'll start again just with the @account feed.