baby boomers mooching on me

i'm getting tired of explaining every little thing to my coworkers.
over and over.  and they've been doing this job since before i was born.
ever since computers took over, they have absolutely no understanding or ability to learn without constant grinding and dog-training. they take notes and never consult them. or they forget which note is relevant. if something requires any interactive care, where the solution might be many steps, they just can't handle it and it gets dumped on me. or it gets done wrong and i have to redo it.
its getting to the point where i am more short and rude with them. or really stern sounding like a disciplinary father. its incredibly frustrating. the work isnt even that hard. and i'm not all that smart. these people are only working here because the bosses are in the same boat. they will stick together until they can all retire and then further rely on me to take care of them at home.