If you need a hassle-free way of signing your apk files, then consider the apk-signer app from Hai Bison. This app is compatible with both phones and tablets. It also supports V2 signing scheme and allows you to manage keystores (import/export).

You can choose to sign a live app as well. Moreover, this app allows you to make your own keystore files and change its overall theme.

It's user-friendly interface makes it easy to navigate. You will find each section or category at the bottom of the screen. Clicking on any of it will take you to four sections: signing (where you can sign the files/apps), apps (where your apps are stored), keystores (where you can check the keystore details), and information.