John Gill Commentary 1 Chronicles 9:26

"for the four chief porters, who were Levites, were in an office of trust, and were over the chambers and over the treasuries in the house of God." — 1 Chronicles 9:26 (ASV)

For these Levites, the four chief porters, were in their set
office
The four chief porters who were over all the two hundred and twelve, and had one over them, (1 Chronicles 9:17) , these were never changed, nor went into the country villages; but were always upon the spot, and in their office, superintending the rest:

and were over the chambers and treasuries of the house of God ;
see (1 Chronicles 26:20) .