A family of Microsoft word processing software products for creating web, email, and print documents.
To ensure that Word fields use the formatting at the insertion point, you can edit the REF field code to include the \* CHARFORMAT switch. (Remove \* MERGEFORMAT if it is present.) Update with F9 (or Fn+F9 on some keyboards). (Strictly speaking, CHARFORMAT forces Word to use the formatting applied to the first character of the field code itself.)
You can control the display of fields in Word via File > Options > Advanced. Choose an option for Field shading. See the screen shot below. To never display shading, choose that option. Some people prefer to have shading shown "When selected" (this is also the default setting). None of these options affect how fields print or convert to PDF.