I’ve always thought that mold is the fungus, and to mould is to shape.
I actually do this too. Not because I think it’s correct as such, but because that way I am consistent and I know what I’m talking about when I read back previous text that I’ve written.
I remember it by Mold = simplified English = simple organism.
TickTick
https://ticktick.com/features
It’s what Wunderlist used to be like before Microsoft bought them and buggered it up, but keeps getting improvements.