^^
To make it more clear for you ... the 590 is only HDMI 1.3 so has no HDMI(ARC) feature and therefore cannot pass audio back to the AVR via the HDMI cable that connects the AVR and TV (unlike it's successor the 591 which can do this). So your only option to pass the TV's smart apps audio back to the AVR is to connect an optical cable to one of the AVR's optical inputs. By connecting it to OPT1 (TV) and setting the TV audio setting to "external speakers" on the TV, you should then hear the smart app audio when you select "TV" on the Denon remote.
To make it more clear for you ... the 590 is only HDMI 1.3 so has no HDMI(ARC) feature and therefore cannot pass audio back to the AVR via the HDMI cable that connects the AVR and TV (unlike it's successor the 591 which can do this). So your only option to pass the TV's smart apps audio back to the AVR is to connect an optical cable to one of the AVR's optical inputs. By connecting it to OPT1 (TV) and setting the TV audio setting to "external speakers" on the TV, you should then hear the smart app audio when you select "TV" on the Denon remote.