You can set position during initialization. For instance, if you have two classes, 'class-a' and 'class-b', then different positions can be set for these two classes as follows:
$( ".class-a" ).tooltip({ position: { my: "left+30 center", at: "right center" } });
$( ".class-b" ).tooltip({ position: { my: "left+15 right", at: "right right" } });