How do I go about changing it and can I do it permanently?
Don’t want to use the .odt, need another suggestion for the format
Please HELP me with this problem
Your question simply doesn’t make sense as long as there isn’t a hint what you acually want to achieve.
If you are using LibO Writer you surely can use .odt - and this will yield the best results.
If you need to exchange files with somone else advice depends on what the other person can accept.
BTW: The common term “file format” is misleading. It’s not about just another bottle for the same water. Flavor may be afflicted irreversibly by transfer.
You could save to .doc or .docx but formatting may suffer in the conversion, especially if the document contains images. Otherwise, you will need to find another Office suite that doesn’t use .odt.
Why do you not want to use .odt?
Edit: “Don’t want to use .odt…” doesn’t tell us why you don’t want to use it and makes it harder for anyone to help you.
Whatever your reason for not wanting to use .odt, your only choices are .odt (the default document file format that LO is built around), saving as a MS file format like .doc or .docx (which may or may not have formatting issues after the file conversion), or to save as PDF (which you won’t be able to edit unless you embed the original .odt file into the PDF or use a costly PDF editing program). Those are your only choices if using LO. If you don’t like those choices, then your only other option is to find another Office Suite, such as MS Office.