In the forum notification email ("you are receiving this email because you are watching the forum ...") it says:

"If you no longer wish to watch this forum you can either click the "Stop
watching this forum link" found at the bottom of the forum above, or by
clicking the following link:"

1. The link says "Unsubscribe Forum", not "stop watching".
2. In the subSilver2 template, the button is at the top but at the bottom. In fact, it is template dependent. I suggest just writing
"If you no longer wish to watch this forum you can either click the "Unsubscribe Forum link" found in the forum above, or by
clicking the following link:"