Need help with arrow legnth
 

I have two older arrows of the same type that I am shooting now but are a good 2 1/2 to 3 inches shorter then the half dozen that I just bought. At 16 yards, the legnth of my basement, I am hitting exactly where I want to with the two shorter arrows but when I add one of the longer arrows for a grouping that longer arrow hits about 2 inches to the right every time.

What does this have to do with the spine and should I have it cut shorter? I hear that the insert is about 1 and a quarter long. What do you think, should I get the new arrows cut and not worry too much about the spine and hunting? Also, I am only set at 61 pounds right now but plan to shoot between65 and 70 after I rebuild my muscles. Should I increase the poundage and see what it does?

Any advice would be great, thanks