I have what ought to be a simple question!
In paradox 9 I have a simple single table database (of documents received in the year). Each year I start another identical table with a new name (by copying the old one and emptying it).
I have a report based on current table. How do I change the table in this report to the new table (to avoid having to make a complete new report)?

Look at the report's data model. You can alias the table name, so that you can substitute a new table in the data model without changing all the fields.

Is to open the report in design mode and change the table to open the report with (in the dialogue window) and then save the report with this new attachment.

Aliasing the table is better because then you will only need to change the alias to the new table each time.

An even simpler method which may not work for you is to simple copy the existing table to a new name for archiving and then emptying the existable and reusing it over again. The report will reflect the empty data automatically.