you can't change them, except by "cheating".
To do so, while the game is closed, in the Tennis.ini (or the .ini of your custom Profile), change this line, under [3dEngine], from :
DevMode = 0
DevMode = 1
Then you could change your strikes in the Outfit configuration screen.
You better set DevMode back to 0 once u're done.
== Mana Games ==
>> I don't answer Private Message, except if it's really a _Private_ topic <<