Font changes automatically

Why does the font change at the end of every paragraph?
I am editing a document in “Times New Roman”, but at the end of every paragraph, the font automatically changes to “Courier New”.
Is this normal? Can this be changed? Can “Times New Roman” be made ‘Default’?

Basic Fonts

If you explain any explanation about the cause of the behaviour, edit (don’t use a comment) your question to mention OS name, LO version and eventually save format.

Such a behaviour usually results from the “chaining” feature of styles. But it should stop after the second paragraph in a sequence. For precise analysis, attach a sample file to your question.