It doesn't matter if you have a Mac or a Windows PC, you can take the assistance of iCloud to keep your files safe. Firstly, make sure the switch on your iPhone's left side isn't set to Silent mode. To scan the QR code, open the Viber on your Android phone, click on 'More' and scan the QR code using the QR code reader displaying in the upper right corner.
How to put password on viber desktop Set a Viber-screen Lock.