You must press the Space bar to start/stop scrolling. Make sure you have checked the option in Tools-> Perferences->Controls Don't know about W7, but that's how it works in W10.
I find the text editor utterly useless. I can't scroll in the text editor window, so copying an element from the bottom of the text to teh top is impossible. I do all the edit in Wordpad.
Weird, I have exactly the contrary. With font size 12 and speed at 1, it's too fast!
You must load the text file in the text editor using Ctrl-C Ctrl-V