Hi Theresa, thanks a lot for the report.
They are really stopped but some apps are able to restart themselves automatically, even after we force stop them for you. That's why you see them listed in Running Apps after you stop them. There's nothing we can do about this because Android doesn't provide an API to stop them in the background and keep them stopped. Instead, we suggest that you not worry about a relatively small number of apps running, and just stop apps when the count gets too high or you want to stop one that's draining in the background. If you don't want these apps running, your only option is to uninstall them.
I generally use the app stopping feature every couple of hours (rather than every 10 minutes), or when I'm concerned about my battery running out soon, or soon after I've been heavily using my device and opening lots of apps at once.
I hope that helps clarify things and we always appreciate feedback like yours.
Jesse, Product Manager