First are they the correct length wiper blades for each side?
Next are there marks both ends of the travel as this can be caused by wear in the linkage allowing the arms to "flop" to far in each direction?
Assuming all of this is correct, then hopefully all you have to do is flip up the plastic cover above the spindle , slacken the 12 or 13mm nut there, push down on the arm about 6 inches from the spindle and if lucky it should release from the tapered spline, keep it in place and try to just move it up to the next spline, make sure it engages correctly on that spline , then holding it down on spline refit and tighten the nut firmly as before and wet the screen and try wipers, fast speed will give max. travel in each direction to check if any fouling.
Note if you have misaligned them be ready to switch off ignition quickly to prevent damage rather than stopping wiper switch as it will still continue to it's park position.
If you follow my instructions and are careful you should be OK, however a Windscreen "specialist" didn't do that on my daughters VW Golf and broke the arm at a cost of nearly £90.!!! Luckily I was there or he may have told her the arm was faulty.