how to disable autoformat to any downloaded file

auto change the file format when i download the statement from the bank could it remain same as downloaded file

Please share here, which OS do you use? Which LibreOffice-version? Which file format does the file have from your bank? How do you proceed? When does the problem occur? Maybe use screenshots and upload them here to illustrate the problem. Describe your problem thoroughly. Maybe you can get help then.

Read these guidelines and ask a good question. A general question: what does you question have to do with LibreOffice?