Hi,
To set which attachment is visible for a slot, click the visibility dot to hide or show the desired attachment in the Tree view. To key the slot's attachment visibility, click the key button next to the slot in the tree, shown orange here:
You can also hide the attachment by pressing the H hotkey while the attachment you want to hide is selected. When Auto key is enabled, you can add the attachment key by simply using this hotkey in animate mode.
