Both phrases are grammatically correct, but they have slightly different word order and connotations:
"Be always happy": In this phrase, the adverb "always" is placed before the verb "be." It emphasizes the continuous nature of the action, suggesting that the person should maintain a state of happiness at all times. It's similar to saying, "Stay happy all the time."
"Always be happy": Here, the adverb "always" is placed before the verb "be." This phrase also conveys the idea that the person should be happy consistently, but it might imply more of a general advice or encouragement to maintain a positive outlook in life.
Both versions are used to encourage someone to maintain a happy and positive attitude, but the choice between them depends on the specific context and the nuance you want to convey. The most common and widely used form is "always be happy."