Faking an answer to look in charge works once. The second time, nobody asks you anything.

Confident guessing passes in the moment and gets found out later, usually when somebody acts on it. After that people stop coming to you, not out of spite but because your answers are no longer reliable enough to use. Admitting you do not know costs a few seconds of looking less authoritative. Pretending costs you the thing authority was supposed to give you.

Next time you are asked something you are unsure about, say so and offer to find out. Then actually come back with the answer. Keep track of how much more often people start asking.