A family of Microsoft word processing software products for creating web, email, and print documents.
The issue may be that your printer is not capable of accurately feeding the label stock. If you print to plain paper, how does the output line up with the label sheet?
When you have your label document as the active document, if you expand the Start Mail Merge dropdown in the Mailings tab of the ribbon and then click on Labels and then when the Label Options dialog appears, click on the Cancel button, the Update Labels button in the Write & Insert Fields section of the ribbon will have become enabled and then anything that you insert into the first label on the sheet will be copied to the other labels when you use that button.