Why is google ranking the wrong site ?

Google is Ranking some kws not for their sites but for another
Example : buy YouTube likes google ranks the buy YouTube views Page
Any idea why ?

those site must have exploited googles algorithm, but that is not going to last long they will get penalised

Google work on the algorithm in which it make rank with the help of keywords

how optimised are the pages and how many times is the keyword(s) included per page?
make sure to have at least some content with the keywords included, exclude any spammy tags used as widgets, etc...
overall, just make sure to have an optimised on-page for your keywords and it has some internal links (external if possible) with exact match anchors