Hi,
@Samanthajayne98 , if you're new to libre, newbies often stick it on the side of the arm. It's way more exposed to random knocks against doorjambs, and things like taking seatbelts, rucksacks and jackets on and off, so it's not so much the stickiness that's a problem, more that it's getting knocked a lot.
I lost my third one to a doorjamb (it's like a rite of passage!) so, since then, I've tended to stick it right at the back of my arm, so it won't snag things so much.
Also, even if we're not hairy, most people have a fine peach fuzz of hair on our arms which we don't really see until we look closely.
That really doesn't help stickiness, so it's a good idea to wash the area down with soap and water to remove any greasiness and run a razor over it to get rid of the peach fuzz, then wait till totally dry, then swab down with the alcohol wipes, wait till that dries, then apply.
Boots do Molnlycke Mepore 7 by 8 cm plasters for about 20p a pop which are good for smoothing out the edges to reduce snagging.
I'd tend to avoid waterproof ones - there's been talk of them preventing sweat from evaporating normally leading to skin reactions but it's all anecdotal.