My mums just got new phone and when she goes too answer a call she has to double tap it, how can I set it up so she only has to tap it once?

[AC Question]

my mums just got new phone and when she goes too ring o2 for top up it keeps locking the phone

she has too keep double taping to unlock it but it locks a few seconds later

 

[B. Diddy]

Re: my mums just got new phone and when she goes too ring o2 for top up it keeps locking the phone

Welcome to Android Central! Which phone?