700 is the speed. 7 is the power for what she has listed up there. White cotton sounds like a tough one-no dyes to burn out and will need to be tweaked to show burn but not burn through. I don’t really work with fabrics, but @MyDogsThinkImCrazy gave awesome advice.
If it’s a natural cotton, I believe there is a post on a canvas tote bag that showed good results. Here is a link to the settings. You’ll have to go to the top to see the picture though, the settings were shared very far down on the post: