Is there a piece of code where I can change a 1 to a 3 somewhere?
It's not done in code; it's done by the database. I have read you can modify the auto_increment value but I have never done this myself. Be sure to make a backup first and verify that everything works as expected. It would be a good idea to verify this on a test site before changing your live database. Be sure to test all relevant payment methods.
The syntax would be something like this:
ALTER TABLE orders MODIFY COLUMN orders_id int(11) NOT NULL auto_increment=3;
OR perhaps just
ALTER TABLE orders auto_increment=3;
I would not recommend doing this but it's your store.
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