A new cello bow?

Well i have these two cello bows...I have used one for a very long time and the other one is brand new which i got with my brand new cello. My used one is a very expensvie one so it sounds very nice and it's smooth. I used it for a very long time so it became the time to change the bow hair. But my parents say use the new one and then when the new one's run out, i can change the old one into new hair. You see, it takes...I don't know...$70 to change bow hair? And we're not that rich so i don't know what to do becasue i'm not used to the new bow...it's so scratchy although i put lots of rosin.....do i have to get used to it or something or is it just a bad bow and should i just stick with my old good bow and somehow get new bow hair?...??????????????