It would be even better if all the fields in the invoices were searchable. I use the note field to enter car details. I often need to find invoices related to a particular car, and it can't be done. I did find a way by generating a sales transaction report, which shows the initial lines of the notes, and then searching its PDF version. However, they have recently modified the format of the sales transaction report and it now shows much less information from the notes. So I can't use this trick any more, not in the way as before. I had to rearrange the order in which I list the details of the cars so that the rego comes first. This way I can still search, but only in the more recent invoices, not all the invoices.
I did submit a request for this improvement more than once before. Is it really so hard to make this possible?