ABC managing director Hugh Marks has confirmed he secretly engaged a recruitment company to look for a replacement for news director Justin Stevens after the two disagreed over the direction of ABC News.

Marks said Stevens “did not know” he had begun an international search for a new head of news but it was a necessary move because they “couldn’t get agreement on the way forward”.

A 19-year veteran of ABC News, Stevens was forced to resign last month after Marks told him he had hired a top news executive from Reuters, Simon Robinson, to replace him.

Marks also signalled sweeping change across the organisation, saying all the ABC’s leadership roles were under review and it was not unusual to “undertake extensive succession planning for all of our key executive roles, all the time”.

“We’ve got to go through some changes, and I guess we can have different views on what those changes should be, and how we go about implementing them,” he said in an interview with Sally Sara on Radio National Breakfast on Tuesday.

Marks said there were “key problems” the ABC had to fix and resources were too stretched across live news. He again indicated some legacy programming or services may have to go.

Now well into his second year in the ABC’s top job, Marks appears ready to start making big changes as he signalled last month on Alan Kohler’s That’s Business podcast. “I’ll give you an example: a legacy television show that has been around for 40 years,” he told the ABC business editor about his plans to axe some longstanding programs.

During the interview on Radio National Breakfast, Sara played him those comments , which he said were “hypothetical”. Earlier, he ruled out that 7.30, a 40-year-old program, was facing the axe.

“A better term would have been: what got us to where we are today is not necessarily the things [that] are going to be successful in the future,” Marks said.

Marks also addressed the controversy that arose last week when the ABC’s hiring of former Australian of the Year Grace Tame to host a podcast about autism prompted Melbourne radio host Charlie Pickering to call the move “problematic”.

Speaking to rightwing live streamer Avi Yemini, Pickering said: “I do actually think it’s problematic, that’s my personal opinion. I think, as a Jewish Australian, there’s a complete misunderstanding of a lot of the words that are said and what [the] true meanings of them are.”

Pickering later apologised for the comments about Tame and also for speaking to Yemini, saying he was “ambushed by a known provocateur”.

Marks said Pickering’s public comments were not a breach of the ABC’s editorial code, and indicated Tame was hired before she made controversial comments about Israel and Gaza.

During an interview on ABC Radio Sydney, Tame incorrectly referred to the rape of Israeli women on 7 October as “propaganda” and “debunked”.

“Obviously, I understand why people feel Grace shouldn’t have a program on the ABC, given you know the controversy that’s reported and associated with many of her comments,” he said.

“I’ve spoken to Grace, and what she really abhors is violence of any kind, particularly violence against women and children, and I think everybody can relate to what she really believes in … The podcast that she’s done is great, and I encourage people to listen to it.”