To apply one PDF sign signature to the same position on multiple pages, please select or create a sign signature firstly.
In version 11, click Fill & Sign tool under Home or Protect tab, then Fill & Sign tab will pop up to create a signature.
In version 10, go to Fill&Sign tab directly to create or select a signature.
In versions prior to V10, click PDF Sign tool under Home or Protect tab, then PDF Sign tab will pop up to create a signature.
After you having selected a signature, click on the position where you would like to place the signature, then right-click on the newly added signature, choose Place on Multiple Pages…. Option in pop-up context menu and set page range, click OK to apply.