You can edit custom (or dynamic) attributes from either the Modify menu or from the Attribute Editor (Attributes > Edit Attributes).
You can perform the following editing operations on custom attributes:
Select it in the Attributes list and modify the name in the New Name text box.
Select the attribute in the Attributes list and then turn on or off the Has Minimum and Has Maximum check boxes, as well as type values for these in the corresponding Min/Max text boxes.
Select the attribute in the Attributes list and then turn the Keyable check box on or off. When Keyable is turned on, the custom attribute appears in the Channel Box.
Select the Enum attribute in the Attributes list and modify the strings in the Enum list the same way you created them.
For example, if you created a vector attribute named Speed, the children would be SpeedX, SpeedY, and SpeedZ. You can’t access the Numeric Attribute Properties (Keyable and Min/Max) of the parent vector attribute. You have to select a child attribute and modify its Numeric Attribute Properties.