Sony has promised to unveil a new strategy by September, to repair the damage done in recent years to its iconic consumer electronics brand.
Sir Howard has been charged with turning around Sony's fortunes
At an annual shareholder meeting in Tokyo, managers acknowledged there had been strategic mistakes.
But new chief executive Sir Howard Stringer also said the firm had spread itself too thinly, and needed to focus on core strengths.
The firm's shares have halved in value over the past five years.
The new chief executive told shareholders that he was aware of his responsibility as the company's first foreign chief.
"I am first and foremost a Sony warrior," Sir Howard said.
Born in the UK but with dual US-UK citizenship, and knighted in 1999, the 63-year old former TV boss said Sony would reveal how it planned to fight back by September.
"We cannot fight a battle on every front," he said.
The success of Spider-Man 2 boosted Sony's profits
Sony is two years into a three-year, 330bn yen ($3bn; £1.7bn) cost-cutting plan focused mainly on slimming down its workforce.
Growth in its media arm - driven by blockbuster films such as Spider-Man 2 - offset its weak electronics showing last year to give it a 15% rise in profits.
In the 1980s and 1990s the firm became increasingly involved with the media industry, buying up Columbia's film studio and music business.
But tensions between the dictates of the technology and media markets have hindered Sony's formerly sure footing.
More than two decades after Sony created the personal music market with the Walkman, Apple has now come to define the portable music player with its iPod.
Cheap competition from other Asian firms such as Creative has also sapped Sony's competitiveness.
Nobuyuki Idei, the previous chief executive, told shareholders that he knew he had failed to keep Sony current.
"I was not able to read the changes" in the consumer market, he said.
The firm still makes two-thirds of turnover from electronics, but has a huge catalogue of films and music which it hopes will help revitalise its performance.