I have a Quantum Muv (Brazilian phone) with android 6.0
When I first got it, its max volume for media was really low, both with earphones and without, so I followed a tutorial to change the settings via engineering mode. It worked well for headphones, but the speakers were still too low. Some time goes by and I try to change the settings again, but now it's like there's no volume 'slider': there's either off (0% volume) or max (all other %es). The settings are all a mess and I'm afraid trying to fix it will just mess everything up again.
Is it possible to reset engineering mode configurations without a factory reset?