If I change my bid amount on a keyword, how long do I have to wait until I see the change reflected in my account?

With any PPC search engine, you should see the change almost immediately, since they operate in real-time using auto bidding software to regulate bids. For example, if your bid has now placed you in first position where you previously were in fifth position, you should see that change reflected very quickly in the search engine. If this is not the case, be certain to contact the search engine immediately and ascertain if there is a temporary problem with their system. If there is still a problem, you may wish to reconsider placing your marketing dollars elsewhere.