Some Google users are having technical issues with changing their search preferences.
The issue appears to happen when you have a default location set and then you try to change another setting. Google may pop up a warning that reads:
The issue is, the user did not change his or her location. They only tried to change another setting, such as turning Google Instant off.
Google’s Laudy said in a Google Web Search Help thread, “Thanks for posting! We’ve investigated the issue and we should have it fixed very soon.”
I personally cannot replicate the issue, so either it doesn’t affect me or it was fixed already.
Forum discussion at Google Web Search Help.