Linux noob need help with dual booting issues

Did you unplug your USB after you reboot to not accidentally boot back into your USB?

There shouldn’t be a ‘manjaro’ user on a new install. That’s only in the LiveISO/USB

You create a user while going through the installation process.


Edit:

I missed this part. You’re booting from the USB… that’s the issue… you keep rebooting into the same LiveISO. You only boot from the USB for installation of Manjaro. Unless you want to run a persistent USB.