Quick answer
What is the difference between following and subscribing?
Subscribing is on your YouTube account. Following stays inside SkipTube.
Signed in to YouTube, Subscribe subscribes you on YouTube, on every device. Not signed in to YouTube, SkipTube offers Follow in SkipTube only. That follow is kept in your SkipTube account and never reaches YouTube.
A box that says Could not update your subscription. Try again. means the change did not go through. Nothing was changed. Check your connection and tap the button again.
A box that says Subscribed to … of …. The others could not be updated. means some of your SkipTube follows could not be subscribed on YouTube. The others worked. Open a channel you want and tap Subscribe to try it again.
Read the full guide: The Subscriptions tab, new videos in one place →