The “Show Bar Nums” combo lets you choose where you want bar numbers to be printed.
Select the “Bar Numbers” checkbox to print only the range of bars defined by the Print Options’ “From” and “Thru” boxes. You can adjust the position of the bar numbers with the “Bar #s Below By” option.
Although I'm not sure how checking "Bar Numbers" is different from just selecting the bar numbers you want. I'm not at my music computer to try it.