High pitch feedback when using headphones

High pitch feedback when using headphones
I get a high pitch squealing when I use my headphones - I have to wiggle them so they are not quite on my ears and it stops. When I move my head it intermittently screeches again. This has been happening for quite some time and I thought it was just me but have now seen other headphones have had similar questions I’m wondering if they are faulty. Any suggestions please ?

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