Please I will like to know what I can do to update some of the applications on my iPhone without losing any data. I cannot operate my whatsapp again cos I was asked to update it and whenever I tried to update; it takes me to the apple account of my sister Inlaw who in turn has forgotten her password. She gave me the phone some years back after getting a new phone and I did successfully logged her out then and has installed my own id but all those apps that she downloaded from iTunes with her account still needs me to log on to her Apple ID. Please your help is needed cos I can't access my whatsapp since yesterday. Thanks

Uninstall the apps and use ur own apple ID to redownload.