John Carr's comment came as new figures show the number of child grooming cases recorded by police have risen by a third in 12 months in England and Wales.
The NSPCC said Instagram accounted for one in three cases in the year to April.
Carr, who's the Secretary of the UK Children's Charities' Coalition on Internet Safety, said: "Any groups that are working with young people can do some great work.
"I've seen great examples of in youth clubs and church groups, scouts, and so on.
"The leaders of these groups need to be up to speed. They need to know what's going on.
"Anybody who works with children who doesn't understand how the internet works and our children use it can't be doing their job properly or well enough, I'm afraid.
"There's a great role for youth leaders in in every area to help."
Figures published by the NSPCC also show more than 7,500 crimes have been recorded in the two years since the offence came into law.
One in five cases involved children aged 11 or under.
Facebook, which owns Instagram, said it has a team of 30,000 people ready to respond to issues around the clock.
Carr said the bulk of the responsibility lies on social media platforms to tighten up security and deal with issues quickly, but parents can't rely on that.
"I think companies do need to step up and do more, but certainly no parent should delegate to a technology company responsibility for their own children.
"The simplest thing to do in my experience is to sit down with your child, get them to get their mobile phone, or their laptop, tablet, whatever it is that they're using. Tell them to show you each of the apps that they're using, ask them about on each app, who it is they're talking to on there, what kind of things they're talking about."
A government spokesman said they have taken strong action to tackle this abuse, including developing artificial intelligence tools to identify and block grooming conversations.
In April it also published an online harms white paper which will place a legal duty of care on social media companies to protect their users.
Listen to Premier's Tola Mbakwe speaking with John Carr here:
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