If the Element Label for a relationship is not specific enough, or is too specific, or you just need to change it to a different one, you can simple choose a different label, as long as the replacement label is part of the same group as the existing label.
For example, 'Author' and 'Composer' are both sub-elements of 'Creator', so you can change 'Author' to 'Composer' or to 'Creator' or any of the other sub-elements of 'Creator'. But you cannot change 'Author' to 'Producer' because that is a sub-element of a different element: 'Other Person, Family, or Corporate Body Associated with a Work'.