John Gill Commentary 2 Chronicles 36:2

"Joahaz was twenty and three years old when he began to reign; and he reigned three months in Jerusalem." — 2 Chronicles 36:2 (ASV)

2 Chronicles 36:14

I am not able to bear all this people alone
The burden of government of them, to take care of them and provide sustenance for them; but he was not alone, for, not to take notice of the rulers and officers in the several divisions of the people that assisted and eased him in lighter matters, advised to by Jethro, (Exodus 18:21Exodus 18:22) , the Lord himself was with him in all matters of moment and difficulty; to whom he could apply at any time for advice, and who had promised to supply and did supply the people with suitable and proper provisions every day:

because [it is] too heavy for me ;
to answer the requests, redress the grievances, and supply the necessities of this people.