s that the same as the link under "edit my subs"? Because if so, itt doesn't seem to work for me; if I return to the page after clicking that, it still shows as if I'm subscribed to everything, and this fact is reflected by any random subsaidit I visit (whether selected manually or by the random tool) showing as if I'm already subscribed.

This is probably because your home page is set to 'all'. Go in your user preferences and change your front page to 'subscribed' and that should fix it. If it doesn't, let me know