About Falloff of Shape

How do I use the “Direction” type in my shape device?I switch them and adjust the parameters as if nothing has changed.

If nothing is changing, you should make sure you have the correct shape selected when adjusting parameters.

For an actual explanation, the direction determines whether the falloff starts or ends at the shape boundary. For External, the falloff will start at the shape boundary (so, for example, the shape mask will be white all throughout the shape, and fade out to black from there), whereas Internal falloff direction will have the falloff end at the shape boundary (so the shape mask will fade to black from the center to the edge of the shape, depending on the distance parameter).