Dealing with unmatched and partially matched stakes

[undervalued]

hi all, apologies this might be quite obvious to some of you

I set a bet of 10 GBP on Correct score market, then later on I green up

I actually take 1 better than market price - sometimes it stays unmatched (even when I keep bet) and sometimes only part of bet (say 5) gets matched. How can I cancel the bet if say it doesn't get matched after 30 seconds and also match the remaining stake if only partially matched (e.g. 5)?

I have tried triggering more than once but then the bet goes in twice? thanks