When you are amused, this means that you are feeling happy because of something that you are doing. For example, when you have just done or watched something that truly entertained you, you cannot help but feel amused about everything. When you say that you are bemused, this means that you are feeling a bit confused about something that you have just witnessed, heard, or did.
You may use the word “bemused” when you want to say that you are feeling confused. For example, you can say, “He was bemused to know that his trusty assistant planned to resign from work.” You can use the word “amuse” this way, “He was amused after she looked at her with love in her eyes.”