What you are apparently trying to do is to "rename" bar 23 to bar 43. The bar number in SONAR is actually the number of measures from the beginning of the project. There is no other purpose for the name/number that I can imagine. If you want to actually move the data following bar 23 to bar 43 (which is actually the only reason I can imagine you would want to change the "number" of bar 23 to bar 24) then you will need to move all the data that far from the beginning, i. e. insert twenty measures after measure 23 in all of the tracks that you want to be so affected. There is no way to simply type that number into the bar number to accomplish this feat.