The reroll button on the die roller is a bit strange; it just takes the new result when it should do one of these.
Edge - use the better of the two numbers
Trouble - use the worst of the two numbers
Instead of a reroll button, have an Edge and Trouble button, that uses the right values.
It would also be nice to see the the original number was.
The reroll button currently prompts you to select which dice you’re rerolling, because an Edge lets you choose which die you want to reroll, whereas a Trouble does not. This also allows you to handle double and triple edges and troubles, rather than needing more buttons for those scenarios.
In this screenshot, I’ve highlighted the 1 to be rerolled, but there might be a scenario where you have a pair of fours and a five, and so want to reroll the five instead of one of the fours.
You can see your previous rolls in the dice roller, as this screenshot shows what you can see the past three rolls. In the example I’m sharing, it’s the initial roll, a reroll with the same result, and a reroll with a different result.
I hope this helps explain what we’re doing with the dice roller and packing all that functionality into one button, rather than making a completely different workflow for Edges and Troubles. 
@joshuamsimons I’m with @digitaljoed having an edge and trouble option would be very helpful, especially while playing on roll20. It would speed up gameplay instead of having to do math (yes basic, but still) on nearly every roll. The way this game is designed, practically every character will be angling for an edge/trouble.
They even have an option for this on the roll20 character sheet, but the Demiplane sheet is far better in every other way.
I see four buttons…
Button 1 - EDGE - Allows player to set edge on each dice that they have an edge for. Changes die rolled with edge color to green, blue for the Marvel die.
Button 2 - TROUBLE - Applies trouble to the highest die roll. Changes the die, rolled with trouble color, to black (grey for the Marvel die).
Marvel die.
Button 3 - TROUBLE +1 - Applies trouble to the two highest die rolls. Changes the die, rolled with trouble color, to black (grey for the Marvel die).
Button 4 - TROUBLE +2 Applies trouble to all three die rolls. Changes the die, rolled with trouble color, to black (grey for the Marvel die).
If these could be added before the roll that would streamline gameplay even more.
A six toggle/check box option could also work…
EDGE 
TROUBLE 
I’ll put the request in so that the rest of the team can take a look into potentially adding the Edge/Trouble button to the Demiplane character sheet.
Edit: Right after posting this I learned that this is currently planned! I’m not sure when it will be available but our dev team plans to add it to the sheet.