First things first I'm going to confess to the sin of trying to recycle a more-or-less ancient x86-64 laptop into a home theater machine. In my defense, that warning is kinda deep in the wiki and the thing is mostly working in terms of being able to run and play 1080p video on the laptop screen and audio and stuff. Regardless, I acknowledge my problems could be damaged hardware or incompatibility. Also this is my first time interacting with Linux, so that counts against me too.
When I try to output video to TV (or monitor, I've tried two different screens so far) via HDMI cable the LibreELEC logo screen shows up on the TV at the same time as the laptop, but the LibreELEC logo screen remains on the TV indefinitely as the laptop goes to the Kodi menu. I'm easily able to get audio out through the TV by changing the audio output device in the audio settings, but I'm not seeing any similar option in the display settings.
I get the impression from searching prior to posting that solutions to this and other problems likely lie in editing the config file, possibly via SSH, but I'm kind of stupid and may need a step-by-step explanation, especially since other advice on that for LibreELEC is understandably for Raspberry Pi devices rather than my silly use case.