Selected theme is forgotten when using different web browsers

Also, i’m not sure if this is done on purpose, but the new Theme seems to only be enabled when set in the browser cookie named ‘preferredTheme’…
What i mean is that, even though i set the new interface to be the default, and it is on the browser that set the setting, using a different browser or computer will go to the old theme…
In fact, if i delete the cookie set by phplist, it reverts back to the old theme…

in order to set the new theme on a browser, i have to either go to settings and re-select the new theme, or visit this url once:

my-phplist-url/admin/?page=configure&settheme=phplist-ui-bootlist

Sorry…
i’m just trying to help, i really love phplist, and i think it was very courageous of you folks to roll out this new theme!

PS: i verified this behavior in Safari, Google Chrome, and Vivaldi, all on Mac

[Moved to new topic]

@petersphilo That’s very useful, thanks. I have reported this to the issue tracker; you can follow its progress here: https://mantis.phplist.org/view.php?id=18574