If the formatted usb is your Solus OS then I don't know.
If your formatted USB is something else, then mount it with gnome-disks (Disks in the menu), and right-click to RENAME.
I've done this before in Disks but I'm not sure the circumstance. It's greyed out when I tried it on my fat32 cross-platform work USB just now. Not sure why. Sorry I couldn't answer definitively.