No Results on Google Search in Normal Mode but Results in Incognito

You can simply add additional keywords to your search. Adding keywords will always reduce the amount of results you get since it uses an AND search by default.

To prove that you can do this even when OR is used, try typing the following into Google's advanced search:

• all these words: a b
• one or more of these words: c OR d

You will notice that it results in the following Google query: a b c OR d

Thus, you can conclude that the OR operator only works on single words. In other words, you can think of your query as a b (c OR d).

Furthermore, if you try to include multiple words in one of the OR text boxes (e.g. let's use d e instead of d), you will get the query: a b c OR "d e".

I had to change my Primary language to English, in my Google Account settings. Not sure if this feature is available for other languages.