Overshooting in Fontself

Hi, I’m using Fontself for about 6 months now and I know the program pretty well. I can’t find anywhere a way to create overshooting. the way I do it is just lowering the letter until it looks the way I wanted to, but it’s very annoying because the changes I make don’t update imminently and from the little preview you don’t really know what you’re doing, so this whole situation is a hit or miss. I want to know if anyone knows how to do it better, and if this is the only way I’d rather know so that I will start to look for another program
thank you for the help:)

*btw. I’m using fontself with illustrator, I make the letters using guides. so before I import the letters to fontself I already know how much overshooting I need.