Bitcoin transactions aren't reversible... I'm confuse

[The Cryptovator]

Look like OP misunderstand about reversible word. Reversible means you can't get back your fund if its confirmed by blockchain. It doesn't mean that you can't make new transactions. If you sent bitcoin to B address then you can't reverse it from A address. If you need it then you have to make transaction from B address to A address again. In a short word, you are not allowed to reverse again from source address that you already transferred and conformed by blockchain. But you are always allow to make new transactions.

[bhadz]

Your example is when you own both addresses. But the real situation to understand what irreversible means for example,
you send me 1BTC, I receive 1BTC. You can't retrieve it or cancel it once sent. It will be returned to you unless I send it back.

[incombit]

Thanks for everybody helped me to overcome the confusion.