@Imtoooldforallthis
I've got two questions, how do bed bugs get in a new mattress and do people with different eyesight see different distances through binoculars?
If you are just shortsighted/longsighted, you adjust the central focus to suit you, just as you would if things were closer or further away.
if your left and right eyes are unequal, you use the central wheel to focus with the left eye first, then close or block your left eye, and turn the right ocular (eye end lens). It screws in and out a bit. So you adjust it so it is also in focus, then, when you open both eyes, both will be in focus. Having done that, you can use the central focussing wheel, and both eyes will stay synchronised. If somebody else will be using the bins, make a mental note of the adjustment you used on the right eye, so you can re-adjust it quickly later. There is usually a tiny scale marked. The left eyepiece does not adjust (maybe on odd, unusual brands they are left-handed).
If they are your own bins, you can put a dot of tippex on the right lens barrel so you can put it back to your own adjustment later.
military bins do not have a central focus, you have to adjust each eye separately. It is sometimes said that this enables you to use one eye for distance, or one eye for close, without having to refocus. Sometimes it is said that it enables you to use one barrel as a telescope, if the instrument becomes damaged.
Some marine binoculars are purposely focussed to long distance only, and have only minimal (or no) eye adjustment, on the grounds that a ships lookout is not supposed to be looking at close things.