Are your dimension arrows and text too big or too small?  A quick fix is to open the properties palette by double clicking on the dimension to change and expand the Fit area of the palette.  In the fit line of this area the scaling factor for the text and dimension arrows is shown.  By changing this number, your text and arrow size will change accordingly. 

A very common scale to print is 1/8"=1', so the fit number should be 96 to match the common printing scale.  Remember, you scale text up to the right size so that it will scale back down and be the right size when you print. 

To use another scale other than 1/8"=1' divide the 96 in half to go to the next lowest scale, 48, or double the 96 to go up to the next highest scale 192.