Not able to add custom label per-transaction, changes all labels for that address

[NicholasLAranda]

Describe the issue

When you're on your transaction list, and go to edit one specific transaction label: if it's in your Sending or Receiving addresses: it will change ALL transaction labels for that address.

Expected behaviour

You should be able to edit ANY transaction label INDEPENDENTLY of the "main" label you specify in your sending or receiving addresses list.