Error Too many related posts

If you scroll down on the left on any post such as https://www.lichtenstadt.com/2018/11/%D7%A2%D7%95%D7%92%D7%99%D7%95%D7%AA-%D7%97%D7%9E%D7%90%D7%94-%D7%95%D7%A4%D7%A8%D7%97%D7%99%D7%9D-%D7%94%D7%9B%D7%99-%D7%99%D7%A4%D7%95%D7%AA-%D7%91%D7%A2%D7%95%D7%9C%D7%9D/ you see the related posts . I tried changing the settings many times and nothing I do makes it save my choice to pull in ONLY 4 related posts. Why is it displaying 15?

The page I need help with: [log in to see the link]