
Hello @Rene Wagner ,
Welcome to Q&A Forum!
According to my research, when make some changes to the Result Source in Central Admin, you need to run Full Crawl again.
Here is my test:
1.Edit the Result Source in Central Admin
2.Start Full Crawl for the Content source
3.Go to the Search Center site (or site collection) Site Settings page as a site admin
4.Click Result Sources, make sure this Result Source set as default. In my test, my Result Source named [Test1202].
5.Go to the results.aspx and click Edit page. For example: http://sp:81/sites/search/Pages/results.aspx
6.Click "Edit Web Part" on the Search Results web part
7.On the Search Reults windows, click "Change query" button
8.Make sure the value of "Select a query" is [Test1202].
9.Save and Publish this page.
Thanks,
Echo Du
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