The beginning of 'Let it go, Frozen' can be notated in different ways. The reading has to be as easy as possible. (Searching for it, I always have the idea that our 200 years old solfege doesn't fit todays music anymore... Read more about this.)

In this one, it's difficult to put the left hand notes on the right places:

In this one, the right hand melody is less nicely notated:

In the third one, the left hand isn't proper: