OnSong uses the built-in text editing capabilities of the operating system so if you are having trouble with copy and paste, it may be due to an operating system update. If you are having issues with the copy and paste menu appearing, you may need to reboot your device.
To do so, go into the Settings app from your home screen. Next, go to the General settings and scroll to the bottom to find the Shut Down option. Tap to bring up a screen to shut down your device. Once the screen turns off, press and hold the power button to start the device again. Once back up and running, open OnSong, and the copy and paste functions should now work.
Keep in mind that the way that text is edited and corresponding gestures and menus are controlled by the operating system and may change when you upgrade. Be sure to read up on these changes to understand new ways you can edit the text in OnSong.