Pages moving in document

I am creating a 100 page document and sometimes pages move around i.e. when I re-open document next day page 63 has jumped to page 65, why is this happening, this has happened quite a few times.

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  • If an individual spread has been allowed to shuffle, select the spread, and choose Allow Selected Spread To Shuffle in the Pages panel menu to select it. If document pages have been allowed to shuffle and you added pages to a spread, choose Allow Document Pages To Shuffle from the Pages panel menu to select it

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