2 Joahaz was twenty-three years old when he began to reign; and he reigned three months in Jerusalem.
*Minor differences ignored. Grouped by changes, with first version listed as example.
Jehoahaz [was] twenty and three years old when he began to reign, and he reigned three (a) months in Jerusalem.
(a) Three months after the death of Josiah, Necho came to Jerusalem, and so the plagues began, which Huldah and the prophets forewarned would come on Jerusalem.
he reigned three months in Jerusalem--His possession of sovereign power was of but very brief duration; for Necho determined to follow up the advantage he had gained in Judah; and, deeming it expedient to have a king of his own nomination on the throne of that country, he deposed the popularly elected monarch and placed his brother Eliakim or Jehoiakim on the throne, whom he anticipated to be a mere obsequious vassal. The course of events seems to have been this: on receiving intelligence after the battle of the accession of Jehoahaz to the throne, and perhaps also in consequence of the complaint which Eliakim brought before him in regard to this matter, Necho set out with a part of his forces to Jerusalem, while the remainder of his troops pursued their way at leisure towards Riblah, laid a tribute on the country, raised Eliakim (Jehoiakim) as his vassal to the throne, and on his departure brought Jehoahaz captive with him to Riblah. The old expositors mostly assumed that Necho, after the battle of Megiddo, marched directly against Carchemish, and then on his return came to Jerusalem. The improbability, indeed the impossibility, of his doing so appears from this: Carchemish was from four hundred to five hundred miles from Megiddo, so that within "three months" an army could not possibly make its way thither, conquer the fenced city of Carchemish, and then march back a still greater distance to Jerusalem, and take that city [KEIL].
*More commentary available at chapter level.