Your screen shot seems to display a tab leader (the dots). You will have to choose a different leader if you want it to resemble an underline.

If you want specific assistance, attach an example document in Word format to this forum. Click the "Go Advanced" button at the bottom of the forums page and then use the options for uploading an attachment.

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Stefan Blom
Microsoft Word MVP

Microsoft 365 apps for business
Windows 11 Professional