If you go to your Google search settings and try to change some of those settings, such as the number of results per page, your geographic region and some other settings, it won't work. Google is aware of the issue and is working on a fix, but it is currently not working properly.
John Mueller from Google confirmed on Twitter that Google is aware of the issue and working on a fix. He wrote earlier this morning:
Thanks! We're aware of the issue and working on a solution.
— John ☆.o(≧▽≦)o.☆ (@JohnMu) May 22, 2018
In the past several hours, I received tons of questions about this bug. So in short, Google is working on a fix and for now, just wait it out.
Here is a screen shot of the search settings page right now:
Forum discussion at Twitter.
Update: This is now resolved.