I submitted the Common App for my Early Action Schools this morning and I accidentally put the wrong number of hours for one of my activities. I put 2hrs/wk 21 wks/yr instead of 3hrs/wk 16 wks/yr. is this a big deal??
No. 20 hours would have been a problem. 42 hours a year vs 48 hours is a pimple on an elephant’s butt.
also would it be okay if I changed this for the other colleges I’m applying to for regular decision?
ok good 
Yes.