shifting notes to the left (into the next measure)

I'm trying to help my 3rd grader transfer a song she made into Musescore. Many trails and tribulations later, the 50 measures are inputted. However, back in measure four, she has some left-hand notes starting too soon, and the right-hand notes get truncated. (That is, you don't hear the 1/2 note from the right-hand as intended because the left hand starts too soon.) I'm trying to figure out how to get all the notes from measure 5-50 to just shift over (move to the left into the neighbor measure). How do I do this?