I got in touch with Infomir support and they sent me these instructions to do a factory setting reboot
Please try to reset your box to defaults and update the firmware according to the following recommendation:
Reset STB to default settings (please pay attention all user settings will be...
I've got all the settings as you said but the volume is still low. There is no Dynamic range compression setting in the inner portal audio settings. My box is a ln infomir 256