He made Solomon king over Israel Not that he resigned the kingdom to him, but only declared his mind concerning Solomon's succeeding him in the throne after his death. Thus David himself is called king, 1 Samuel 16:1, because he was appointed and anointed to be king after Saul's death, though till then he was only a subject.
Related Commentaries of 1 Chronicles 23:1
1 Chronicles 23:1
1 So when David was old and full of days, he made Solomon his son king over Israel.