Just to confirm, did you recently subscribe to the channel? If the sub button isn't showing "subscribed" try refreshing the page (sometimes there's a short delay). Otherwise, send us screenshots and details of what you're seeing and we'll go from there. Thanks.
That doesn't seem right. If you're using a shared computer/device, consider signing out of any Google services when not in use. It is possible that you're still signed in while someone else browsed through YouTube and made changes. If you notice anything else, let us know.