Your Roku Activity, for example, should not have the arrow keys allocated to the TV they should be for the Roku. Then create a Macro within the Activity that “calls up the Samsung TV menu, arrows left, down, down, right, right and then hits OK twice to switch to HDMI/ARC output and once to switch to TV Speakers and the exits the TV menu”. Once the Macro has completed the arrow keys will be as they were before the macro was used, set to the Roku. Then do the same for your Apple and FireTV Activities.