On Wednesday, June 9, 2021 at 10:14:25 AM UTC-4, Scott Lurndal wrote:
Nil writes:
On 08 Jun 2021, Marilyn Manson wrote
in alt.home.repair:

I'm really just venting but also sort of hoping that someone has
other suggestions to try before I do the factory reset. No, there
is no "Default Power On Source" that needs to be selected in the
settings. If there is a signal at the HDMI port, it's supposed to
default to that.

My Samsung TV remembers its most recent input and will return to it
when you turn it on. This seems like the most logical way for it to
work.
Many "smart" TV's support CEC device control. If enabled on the
TV, it will automatically switch HDMI ports if or when the device
attached to that port is powered on or changes state.

There is usually a menu item on the TV to disable CEC control either
globally or on a per-HDMI-port basis.

This is usually the cause of unexpected HDMI port switches by the TV.

https://support.google.com/chromecas.../7199917?hl=en

Samsung's version of CEC is Anynet+.

It was/is set to On. Turning it off made no difference so I turned it back on.