How do I restore default values in an excel drop down

Example: 1st drop down : NorthAMerica, Asia
2nd Drop Down: IF NorthAmerica is selected then( United
States, Canada)
If Asia is selected from the 1st
drop down(Japan, China)
1st run: if I select N.America from first drop down and select United
States from the 2nd drop down.

2nd run: I go ahead and select Asia in the 1st filter but the 2nd filter
remains United States and I have to manually go aheah and select Japan or
china

IS it possible that if I select Northamerica, it doesnt' show anything till
I go and manually select the 2nd filter?

SOrry for my long essay, but I am very desparate to get an answer. Any help
is appreciated!