Find the ldc.i4.0 entry (for false) that represents the boolean you want to change and edit the 0 to a 1.
If you're trying to change a boolean and the operand is set to none, I'm not sure you're looking at the right entry. Got a screenshot?
There's no reason it would display the true value in green, it being red is fine. The debug menu is no longer linked to the Create Menu, and hasn't been for a while, so that's why you can't bring it up.