Hello, I’m Nathan, and I’ll be assisting you today. My livelihood depends on your positive feedback, so your satisfaction is my highest priority.
Sorry to hear you’re having trouble.
The setup you are wanting is outside the intended scope of use for this type of system. The bose is meant to be a replacement for the internal speakers, not something you toggle back and forth, so you can't really have it where you can easily switch between then and still have a limited number of remotes.
The ARC connection can work, but in reality does not work as well as it was designed for, especially when mixing brands. If you had an LG soundbar it would be a different situation.
The easiest option for you would be to keep things as they are now (for cable), and run a separate optical cable from the tv back to the bose.
You'd keep the bose set to the hdmi input (from cable) and the tv set to the hdmi input, for watching cable tv.
On apps, you'd flip the bose input over to optical when you want to use it, and mute the tv speakers. For using the tv speakers only, use the lg remote for volume and just turn the bose off.