What you can do to stop taking a moving current price to green up is this.
Using the ladder, keep clicking the current price box (I'm doing this in horseracing in-play so it is changing fast) - this transfers the greening price you want to the manual box - then click the manual button and this will fire in a request for the value you want rather than the fast moving current price.
Of course you need to check the manual box is green (and you haven't transferred a quickly moving current price that is red) before clicking the manual button.
Not guaranteed that you'll get the price you want but you won't get something you didn't think you were asking for.
I hope that's clear as it sounds a bit muddy to me.
Seabird