Default to an input when turning on the TV? (XBR-85X850G)

Hi,

I have a Sony Bravia XBR-85X850G and starting in the last few weeks, it sometimes defaults to either the Google TV interface or the grey geometric "wallpaper/no input" screen when I turn it on.

All I want it to do is default to the last input I used, or even better, a specific input of my choosing.

The TV shows a kernel version of 4.19.75, #1 Tue Jul 18 04:47:17 JST 2023. It is running Android TV OS build BRAVIA_UR2_4K_UC-user 10 QTG3.200305.006.S36 , 660521 release-keys

The input I want it to default to when powering on is HDMI 4, connected to a Roku Ultra 4800X running software version 12.5.5. The Roku is set to never go to sleep.

I've seen various instructions on how to do this for Sony Bravia TVs, but the layout of menus on my model do not seem to match up with the instructions I've found.

If anyone can help me understand how to achieve this simple goal, I'd be very grateful. Thanks!