Don't touch what may look like clips at the edges - they aren't they are a solid moulding.
Grab top edge of filter, and pull top edge towards you. The filter will deform, and pop out from those "clips", then lift out.
Refit is slot bottom of filter in, then bend the top edge of the filter, and tuck the top corners behind the "clips", and push the top middle in last. Filter's shape will hold in. Refit is obvious once you start 

I'm shocked anyone would say that let alone an experienced admin.

they must have been changing pollens filters wrongly for years

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they are clips and they do unclip, rotating outwards, away from the filter face. then pull back the filter a few mm, slide it out, no need to deform it or bend the new one

, slide new one in locating it at the bottom, then the clips click back in, pushing the filter into place. simple

looks like you learn something new every day on oof. even if you don't agree with it

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