Time limits don't work

No matter what I do with the time limits for my kids and their PC, they are able to use it. e.g., I set it to allow them 1 hour a day but they used it for several hours. (Specific website blocking does work, however, so there's no doubt that Norton Family is up and running.) I recently installed Windows 10 on their machine. Interestingly, the Microsoft Family Safety time limits are also being totally ignored.  The problems are also true on a separate laptop, which has Windows Vista. The kids use their own non-admin user account on each computer. Help would be appreciated.