As an appointee you’re responsible for making and maintaining any benefit claims. You must:
sign the benefit claim form
tell the benefit office about any changes which affect how much the claimant gets
spend the benefit (which is paid directly to you) in the claimant’s best interests
tell the benefit office if you stop being the appointee, for example the claimant can now manage their own affairs
If the benefit is overpaid, depending on the circumstances, you could be held responsible.