Have been = something is continuing from the past Had been = something has stopped. I have been having a lot of sleepless nights = this was happening regularly, and is still happening I had been...
Has been is third person singular - he has been, she has been, it has been. Have been is anything else - I have been, you have been, we have been, they have been. It is the past continuous tense,...
The verbs 'have been' should be used in case of all first, second person nouns and in case of third person plural nouns. The verbs 'has been' should be used only in case of third person singular...