Hey guys just a few questions . I’m new to the dslr camera world and recently got a Nikon D610 slightly used as a floor model . I’m having a hard time figuring out some things . For some reason the sub command dial won’t change the aperature . I’ve messed with the command settings and so I know that the sub command dial works because I’ve used it to change exposure . But the aperature stays at f16 . And also when I hit the info button , the screen flickers at times to bright then a darker gray color but all the info still shows . Any help would be awesome thanks