Keep UserForm Linked To Particular Workbook Even If Focus Is Lost

I have an excel program that uses a modeless userform. often times i will open other spreadsheets while the form is active or minimized. if i return to the form and run it without manually bringing focus to the appropriate workbook, i get an error because it references the wrong workbook. is there a way to keep that form tied to that workbook no matter what? also, it is important that this procedure works despite the workbook name changing.