The word ‘button’ is often mispronounced by Swedish speakers of English so that it sounds like ‘bottom’.
Also, the word ‘backside’ is frequently incorrectly used instead of the word ‘back’.
A backside and a bottom are the things we sit on (also called a bum, buns, ass, behind, hiney and (in America anyway) a fanny)
so you would say
– press the button
– I always press the wrong button
– I have a flower in my buttonhole (not bottom hole)
or
– the back of the paper
– the back of the building
– the downside (nackdel)