My printer does not have a setting for plain paper. How do I edit it?
What are you trying, what paper types do yo see in the properties of your printer device. And generally speaking - each printer should have some “plain” paper setting which just means “standard” paper for printouts - just the name used by your printer device may differ.
If you really expect a useful answer, edit your question because my tired fortune teller was unable to guess your printer brand and model, despite all his efforts with voodoo incantations. You tagged question as “common”, does it mean you experience the same difficulty with all LO components (Writer, Calc, Draw, Impress)? If so, it might tell something is wrong in your OS (which one?).
Last, but not least, what is “plain paper” for you? I know of the DIN Ax series format, but it could also be related to paper fabric (as opposed to bright photo paper, thick paper, cardboard, very thin paper, …).
Are you the same poster as @Scorphitman who asked the same question? It is perfectly useless to ask several times, you only arouse those who would answer.
If you are impatient to receive an answer, first ask a relevant questions whose whereabouts can be understood. To bring back the question at top of the list, just edit your question with new elements. Otherwise you risk deletion of the question.