Step 3 is rewriting passive sentences into active ones.
Or most of them, at least.
You want sentences that are subject-verb-object. Not “25 invoices were tested” but “we tested 25 invoices.”
Searching your text for “was” and “were” can help find your passive sentences.
Also search for “It is” and “it was” and rewrite sentences that begin with those phrases. They are dummy subjects so change those sentences to start with the actual subject.