How can I change my site to default to light mode for everyone/new people?

Trying to make light mode the default for my site instead of dark mode, but have dark mode as an option for users. On my current theme, it is set to Light.

I checked the colors for it and it is indeed set to #FFFFFF (white) as the main background color. “Color scheme can be selected by users” is checked. My “default dark mode color scheme id” setting is set to the dark version of my theme. My browser has any dark-mode extension turned off.

In your admin - appearance - themes settings, make sure the settings for the default theme looks like this, and that in color schemes, the color palette is set to a light palette:

and that a dark palette can also be be selected by users:

Of course users will be able to override this with their user preferences interface settings or with the sidebar buttons.

Wait, I should have “theme can be selected” OFF? Yeah, as shown in OP, my color scheme is definitely light-color. For palettes, I have my light theme, the dark theme for that one specifically, and then a separate custom dark palette that I made selected as my 3 options. Not sure why dark keeps showing as default.