They're all correct, but have different uses.

They're all correct. The tenses are different so they refer to different times.

They do that don't they though?! Exercises. Confuse... Can you work out which is which tense? I'm a native Britsh speaker and linguist and professional teacher of decades experience - and I really glaze over whenever I see them written in this format (side by side) - so this begs the question; 'What's the best way to learn this stuff?'. You know the answer, really, dont you? And you know this isn't it; posting it in a forum... Mme. Ten points to you, if you knew it was to book a teacher and chat through these various scenarios using real conversation. And then maybe weave them into conversation pieces over a few weeks while enabling you to gain familiarity with correct diction, syntax and pronunciation; and who knows which tangents? And then you'll find them sprung upon you again by that clever teacher who will return to them according to a learning plan (because you recognise the benefit of a repeated commitment to the sessions) rather than just some random chit chat with another equally clueless learner 'somewhere in the world' 'when they get the chance'. And, if you teacher is worth their salt, they'll encourage you to also maybe even practise recording these (and all manner of useful speaking points) over a device and sending them at all sorts of hours ('when YOU get the chance') to your qualified teacher who cares ABOUT YOU enough to smile with joy at your drive and commitment so much that they won't care about assessing and remarking upon your efforts when really they should be doing something else. And this is what will move you forward. Thank goodness for your teacher.

Different contexts..