Currently you can only assume a loss. I can change this in the next update so that an option to assume a win is added. The problem may occur though where you can not tell whether the bet was resulted or timed out as the win string may be 1 or "Won" or similar.
In regards to
Also, when I edit the win/lose string in the mastertable so that it reads "1" or "LOST" and then hit reset bets in progress, it changes to "Assumed Loss". How do I edit the win-lose string so that TSM recognises it?
Once you have changed the Master table data always update the results grid. This will 'save' the changes.