PouchDB Data lost after App Closes

tutorials
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Hello, I am new to Ionic and PouchDB, and, currently having issues with PouchDB where I am unable to call the same database whenever the app close. I am suspecting my database is still there but cannot be accessed because from the Android device that I use to test, local storage and cache does not gets cleared when the app closes. But everytime I open the app, there will be no data displayed, and I need to re-enter all of test information again.
I have researched on the topic and cannot find much aside from pouchdb-data-gets-deleted-after-app-quits issue.

The way I open my database is simply using;

var db = new PouchDB('testDB');

Below is my ionic info;

cli packages: (/home/pc/test_app/node_modules)
    @ionic/cli-utils  : 1.15.0
    ionic (Ionic CLI) : 3.15.0

global packages:
    cordova (Cordova CLI) : 7.0.1 

local packages:
    @ionic/app-scripts : 2.1.4
    Cordova Platforms  : android 6.2.3 browser 4.1.0
    Ionic Framework    : ionic-angular 3.5.0

System:
    Android SDK Tools : 26.1.1
    Node              : v8.1.2
    npm               : 5.4.2 
    OS                : Linux 4.10

Environment Variables:
    ANDROID_HOME : /home/pc/Android_Studio/SDK

Misc:
    backend : pro

here is my package.json

        "pouchdb": "^6.3.4",
        "pouchdb-adapter-cordova-sqlite": "^2.0.2",
        "pouchdb-adapter-localstorage": "^6.3.4",
        "pouchdb-adapter-utils": "^6.3.4",
        "pouchdb-adapter-websql-core": "^6.2.0",
        "pouchdb-binary-utils": "^6.3.4",
        "pouchdb-browser": "^6.2.0",
        "pouchdb-collections": "^6.3.4",
        "pouchdb-core": "^6.2.0",
        "pouchdb-errors": "^6.3.4",
        "pouchdb-json": "^6.3.4",
        "pouchdb-merge": "^6.3.4",
        "pouchdb-promise": "^6.3.4",
        "pouchdb-utils": "^6.3.4",