Some people find some or all of the items in OOo’s AutoCorrect function annoying because they change what you type when you do not want it changed. Many people find some of the AutoCorrect functions quite helpful; if you do, then select the relevant options. But if you find unexplained changes appearing in your document, this is a good place to look to find the cause.
To open the AutoCorrect dialog, click Tools > AutoCorrect. (You need to have a document open for this menu item to appear.)
In Writer, this dialog has five tabs.
The AutoCorrect dialog in Writer, showing the five tabs and some of the choices.