Tessa,
We think it will reset on its own in 24 hours .... otherwise you need to delete the cookies. I believe that's probably an option in your browser.

Here's someinformation from the forum site:

no messages will appear as "new" on your first visit to the board, or on your first visit after deleting your cookie files.

If you've visited the board several times, and the notices still aren't appearing, or aren't appearing correctly, you may just need to delete your cookie file and start from scratch.

The script considers a new visit to begin once you've been away from the board for at least thirty minutes, so if you return to the board before half an hour has elapsed, the "new" notices will not have updated.

Finally, messages posted since the beginning, rather than the end, of your last visit are flagged as new. So your own messages from your last visit will be so flagged. This may seem a bit confusing at first, but it's actually handy, as it makes it easier to spot new responses to your messages. As well, any messages posted by others while you were busy posting messages will also be flagged as new on your next visit, so you won't risk missing them.

Hope that helps,
Kitty