No offence:
It is my understanding that amendment is a change in the words or meaning of a law, contract, agreement or document (such as a constitution).
Please make amendments according to the attachments (at the back).
Apart from that, there are no major problems on the other designs.
** attachments are usually put at the back of the proposal/report/..., in that case you should say according to the attachments at the back to make it more formal.
**If the attachments are put on the same page of what you want to make modification to, you should say 'please amendments according to the notes written on the corresponding page(s)'
參考: Myself (I am an English mentor and write English books)