Attribute/Options-List extend/edit

[RobertinoM]

I've created an attribute list for compatibility with software named app_compatibility
 
I creates a list of options like in the example
 
the selectable options have the following values 
Windows 95
Windows NT
Windows 2000
Windows XP
Windows Vista
Windows 7
 
so far so good... but now we have new windows versions  Windows 8/8.1/10 and ii have to extend the list of options but how? 
 
 
when I go to "edit attribute" I have all settings like search etc. but no way to extend the list
 
does anyone know how to do that? 
 
regards robertino

[RobertinoM · Accepted solution]

Okay... sometimes... we were sitting in front of it with three guys..  nobody has seen the button

Problem solved