I right click on the taskbar and go to 'Properties' then 'Taskbar' then
'Customize' to get to the Customize Notification section. When I click on
either the Current Items or Past Items a drop down menu appears under
Behaviour. However there are no choices other than 'Hide when inactive',
there is no 'Always hide' or 'Always show'.
Why are there no choices and how do I change it?

Thank you.