Forum Moderators: Robert Charlton & goodroi
The reference to your "own former search keywords" suggests that it is a personalized search feature, which they may be testing, or they may have rolled out as a general new feature.
Chances are they assume that when you repeat a search a lot, it's because you didn't find what you were looking for before.
Otherwise, though, the Yahoo suggestion feature seems to leave my search choices alone. My last search stays in the search box until I delete it and type in something new... pretty much the same as the plain vanilla Google.
I'm not seeing what you're seeing on Google, so, if you're not signed in, the feature is likely experimental. I'm not understanding from your description exactly what it's doing.