When Charles V became Emperor of the Holy Roman Empire he was left the very difficult task of controlling several different countries and territories all over Europe. In the 16th Century traveling from country to country took a long time. Transport was obviously not as advanced as it is today and so it was no mean feat. Therefore it wasn't as if when there was a problem in Spain he could jump on a plane and be there within an hour or two, it would take weeks to travel across Europe and so things were incredibly difficult for...
was mainly the way that things were being run within Germany that lead to the spread of Protestantism. Charles had too little power within Germany to have any bearing on the Princes decisions.

It was difficult for him to raise an army too and so he couldn't use force against them.

The main reason for the spread of Protestantism was the poor way in which the Church and Charles dealt with Luther at the beginning. They let it go on too long, and then his campaign built up momentum and it was too difficult to stop.