Custom tool box

I am trying to edit a custom tool box that I created 4 years ago. The tool box is really simple, it just sets up attributes  for given features that we want to place.

For some reason I can no longer edit this tool box to add more features or edit existing ones. When I right-click in order to add or edit a tool the option to do so is dimmed/greyed out.

I've looked through the forum but everything is outdated or completely unrelated to my issue.

Any guidance will be appreciated!
Thanks in advance!