Change Vue.prototype value in route page

Vue.prototype.$myname= 'xxx'
and in another (f7 route)page im changing it as
this.$myname= 'yyy'
navigate to another page using
and in that page button alert(this.$myname) gives xxx
wht im doing wrong ? it is a framework7 vue v1 app

This is how prototypes work in JavaScript. Use better $roo.myname to exchange data