This is caused by a setting in the Options menu. To prevent this message appearing you can do one of two things:-
a) PosApp v4-00 and v4-01 (including all SR releases of these versions) had this menu option default to 'on' / 'ticked', which was unintended
b) From PosApp v4-02 onwards the default state of this menu option was set back to the intended value, i.e. 'off' / 'unticked'