Conditional formatting based on a checkbox

Howdy y'all. I'm trying to format a spreadsheet being used for a golf outing. It's not a big deal, but it will satisfy my OCD if I can click my "PAID" checkbox, and it will highlight the row with the person who has paid. Should be fairly simple and straight-forward, but it's giving me some headaches.

So far with all of my formatting, I've been able to just use IF statements to make everything work, but in this situation, it's not going to work that way.

Excel AND the internet want me to just use the formula in the conditional formatting window =M7=TRUE (and obviously cascade this down for each line beyond 7), however this is only highlighting the initial cell; when selecting B7:I7, the formula will only cause B7 to format, and the rest will not, even though when I click on each individual cell, it's showing that the formula is applied to those other cells.

I'm really trying to not have to individually format like 500 cells if I can avoid it.

Also, if I cannot come to a solution, I guess I will just suffer without the highlighting. lol

Thanks ahead of time!