[Koha] Pls. help

Dear All, We have been creating Barcode Label for Books in our Library. By default it is taking the Font size 8 while printing. We want to change the font size of print. We also want to mention the acronym of our Library on the Top of the barcode Label. We have not found any remedial option on Koha admin. Kindly help. Bibhuti Nath Jha