My armrest creaks a little when a passenger leans on it thanks to a work colleague who I car share with who think the armrest's purpose is as a prop to raise themselves up occasionally (and I don't want to offend them by saying stop it), rather than simply resting their arm on it.

I'm wondering though could the creaking be occurring because they have loosened the mechanism and it simply needs tightened or whether a good lubricant on the right locations would stop it? Has anyone any ideas? If so how do I even access the mechanism that keeps the armrest propped up?
Thanks in advance,
col_85