Ionic serve not refreshing

when I install Ionic 4 everything is fine and the browser refresh the app,
but when I use Ionic v3 It doesn’t refresh and i should type ionic serve every time I made a change.
I want to work with Ionic v3 because i want to attach a pre fill database, for that i need www dir to place my Db and i can’t find it in Ionic v4
I hope you understand my weak English
Thank you in advance