After iOS10 Update - Voiceover-Speed change does not work

Hi, after I have make the Update to iOS 10 on the iPhone 6 of my blind woman, the rate of speech VoiceOver can not be changeg - I can slide the controller from left to right , but the tempo remains unchanged too fast . Please correct this error as soon as possible because my wife needs her iPhone urgently for their work . Thanks & regards from Berlin

Message was edited by: SpacyTrancer