yes it is necessary to screenshot every transaction you make, either Bitcoin transaction or bank transaction is very important to screenshot it. when we're still using binance in Nigeria, I pay for a particular coin, the seller of the coins do not want to release the coin for me, I chart him up that he should release coins that I have paid, no response so I quickly go to appeal, and they asked me where is the screenshot of my payment. I forward it to them immediately and binance write him that within one hours, we should settle our seif immediately he released the coin. so if not the that I screenshot the payment receipt, that is how my money would have Lost.