Jack Cork headed home an 84th-minute winner after Jay Rodriguez had cancelled out Barry Nicholson's opener for the hosts, who have yet to win since Brown took the helm.
"I need them to understand why we are conceding goals," said Brown.
"The first goal is a nonsense in terms of our defending - we were comfortable up till then. It is basic, fundamental defending we have to get right.
"Bragging rights go to Burnley this week and I can't stand the sight of 5,550 supporters enjoying themselves at Deepdale.
"We forgot to play when we got the ball, but we didn't hold the ball up when we got it up front. I need better quality in both final thirds. We've got 13 games to try and put that right."
Source: PA
