do you mean just the popup property or the the modal property as well? acDialog will also set the modal property which means user cannot leave the form until they close it.
If just the popup property then in addition to ranmans suggestion, in each form open event put the code
me.modal=false
a shorter version to ranmans suggestion (and corrected the *)
docmd.OpenForm "fMyform",,,,,DCount("[userid]","tUsers","[UserID]='" & vUser & "'")*-3