So, basically I reviewed this item (改める) today and got it wrong.
For some reason I mistook this for 収める (which btw. also wrongly accepts “to stack” as correct meaning ) and I entered “to stack” as meaning, it was correct and when I entered the reading I though it was (おさめる) it was wrong. Then I saw it was wrong, checked the reading and saw “what… あらためる?” then I checked the meaning and… oof, I was completely off. But why did it accept “to stack” as correct answer?
Anyways, I wanted to report this. And while you’re at it, like I mentioned 収める also accepts “to stack” as correct answer :'D
Both things you might want to change.