The only way I can think of is to edit the legend command:
>> edit legend
and modify these lines:
% set location if empty
if isempty(location)
if ~is2D(ha)
location = 'NorthEastOutside';
else
location = 'NorthEast';
end
end
Although this is a simple edit, you might want to make a backup copy of legend.m before you edit it, just in case.