Let's move on to had better. Had better is stronger than should and ought to. Had better carries an indirect threat. For example, if you said, "You had better finish the report," you are not making a polite suggestion. You are making an indirect threat. In other words, if you don't finish the report, you are in trouble. Authority figures sometimes use had better when speaking to people below them. Parents also use this form often.
Had better is not always impolite, it could express a sense of urgency as in, "Your plane is leaving! You had better run!" In other words, "If you don't run, you will miss your flight." Had better has no past tense or question form.