I saw these examples, but I still cannot figure out the difference. When should I use with and about with the word happy?
Are you happy with this arrangement?
I’m not very happy about the children being out so late.
According to this author there's a subtle difference between the two uses:
be happy with = be satisfied with something you possess or have experienced;
be happy about = be pleased by; be glad that something happened.
However, the author concludes:
Nevertheless, you will hear some native speakers use the two expressions quite interchangeably, so even if you confuse them, you will likely be understood.
This said, if you want to be as correct as possible, you should treat the subject with due care.
Generally, one would claim to be happy WITH something in which they are involved, something local, or some situation to which they contributed.
I am happy with my schedule.
Generally, one would claim to be happy ABOUT something in which they played little or no part, or something global.
I am happy about the weather.