How can I amend any unmatched bets I have?

How can I amend any unmatched bets I have?

You can amend or cancel an offer at any time up to the point at which it is matched or when it expires.  You can do this by looking in your Current Bets, clicking on the bet in question, and changing the odds or the amount, or indeed cancelling the bet.

You cannot amend the terms of a bet after it has been matched.