Look for a different solution.
The scrolling of the units doesn’t lock but you still have to scroll the screen to see the answer so you have to be very careful of where you touch on the scree. Also if you go from mass to volume to mole it doesn’t keep your last used conversion for any of those categories so you have to scroll again. This is more of a pain. I’m going to look for something else to use. Wish I wouldn’t have paid for this.