Can standing all day for years bent over a computer cause hems to get worse and bleed?read where it is sitting that causes them but not standing.

Several: Constipation, firm large stools, dependent situation-standing -sitting- hemorrhoidal veins full and pro lapsing. Exposed tissue gets irritated, ulcerated, oozing- bleeding.

You're partly right!: Anything that increases pelvic pressure to engorge the hemorrhoidal blood vessels will make them bulge--so if you sit for hours on a couch, have a desk job, strain hard at stool while sitting on the commode, then get up (!), change position, stop straining, walk a bit. See other healthtap answers regarding hemorrhoids & their differential diagnosis (ie. Are you sure you just have hemorrhoids?).