The Wallabies were felled 22-15 by Fiji in Saint-Etienne on Sunday, plunging their quarter-final hopes into jeopardy.
Australia face Wales in Lyon on Sunday for a do-or-die Pool C battle, and ex-England boss Jones admitted going back to the drawing board.
The Wallabies have lost prop Taniela Tupou and lock Will Skelton to injury, and Jones conceded that without their main power forwards Australia have had to concoct a new gameplan.
Jones was the latest special guest on Lawrence Dallaglio's Evening Standard Rugby Podcast, talking candidly about his second stint as Australia boss and all things World Cup.
"Tactically we need to play a little differently," Jones said. "We've lost our two power forwards and they allowed us to play a certain way to get on the front foot.
"So against Wales we'll have to rethink that, so we're in the process of coming up with some ideas there.
"It's always difficult after a loss, you've got to front up and do what you can. As head coach I always take responsibility for the performance.
"We decided to go with a young squad to rebuild, and sometimes it's tough for a young squad to respond within games. That's my responsibility.
"We've got the opportunity to do something now. These are the weeks as a coach and a player you feel the most humble. So we're looking for a galvanised performance this week."
Australia could still reverse their current plight and even set up a quarter-final with Jones' former employers England.
The 63-year-old was dismissed in December after England's worst calendar-year set of results since 2008 with six defeats in 12 Tests.
"When I watch England I still have a lot of affection for them," said the former Japan boss. "I love the players, I don't have any bad feelings towards any of them at all.
"I had a great run there, seven years. Imagine an Australian coaching England for seven years – it's the most contradictory relationship you can have in the world. I loved it and had some good success. It didn't end well but it very rarely ends well."