McDermott, who steered Leeds to victory over Sheffield Wednesday in his first game in charge, played Varney in a more accustomed central role up front alongside Ross McCormack and was rewarded with a two-goal haul.
"I must admit I took it too literally in a 4-4-2 at the start of the season," said Varney, who had been asked to play in a wide midfield role under previous boss Neil Warnock.
"I'd never really played left midfield. When I start a game, it's in my head I have got to tuck in when I want to get the ball further up the pitch.
"When I'm wide, I have to get crosses in and that's not really me. I don't assist in goals.
"I'd like to think I can get in behind and in on goal. I do miss a few chances, but like to think I put as many in."
Leeds secured their first success in eight games on Saturday and back-to-back home wins would see them take another big stride towards guaranteeing safety.
"It's been instilled in us to be positive and have no fear and that is what we will do," Varney added.
"I'm sure we will go into Tuesday night positive. We've not had many good midweek results here apart from the Blackpool one and hopefully, it's one where we can start well and keep that mentality of passing and getting forward and having no fear of getting on the ball."