How do I remove this annoying script editor option?

I usually script on a mac-book, but when switching to windows I noticed this very annoying feature of Roblox studio. It is when you are trying to edit your code and instead of you being able to edit where your cursor is, it will highlight the letter in black, and will not allow me to edit in that specific spot. Instead, of placing letters where my cursor is, it will just start replacing the rest of the line. This makes it very annoying to edit code. Can someone please tell me how to fix this.