This Computers Retreival of all information looked at from the past half hour?

Question

im in an internet cafe and needed to go where you cannot go for me. Stupidly forgetting to sign off. When I came back (I saw a male sitting on my chair with the computer still signed into yahoo questions) though i did not see if he did anything to the computer in my absence, is there anyway i can find out help if anything was done to this compouter in my absence. I do not know why he was sitting on my chair.

Answer 1

short and simple answer, do not use public access PCs for anything personal!

Answer 2

what could he have done to a public computer apart from go online??

check internet history to see if he looked at anything he shouldnt have been and tell whoever is responsible for the computer incase anything comes back from it.