I'm trying to set Chrome as my default browser but cannot. I go to apps and the clear default button is not enabled and says no default is set.
You don't have to go via your browser (Chrome, or some other browser in this case) to reset your default app settings though, you can do this from Settings > Apps. Click the "settings" dots in the top right hand corner and then choose "Reset app preferences". Your phone will now reset all app preferences and start asking you again what browser to use.