I work on a Surface Book with a small screen. When I try to sign a pdf doc the dialog box is huge and extends well past the bottom of my screen. When I try to scroll down to the click the OK button after I enter my signature or initials I cannot scroll

I work on a Surface Book with a small screen.  When I try to sign a pdf doc the dialog box is huge and extends well past the bottom of my screen.  When I try to scroll down to the click the OK button after I enter my signature or initials I cannot scroll down far enough.  Also, the dialog box does not respond to dragging it up on my screen. End result is that I cannot sign or initial pdf docs.  Help!