I’m am able to reproduce the behavior reported by @Matthew_Beery , and I have done some tests. All tests are on the same computer, and I did not reboot between tests (nor was I consistent about clearing the cache), so some of my conclusions may be inaccurate. Edit: Also, I never fully closed the incognito Chrome browser I was using for tests, which drastically changes some of the behavior reported below – apparently, all cookie-derived information is cleared when the incognito browser is closed, and any existing cookies are not reloaded when opening a new incognito browser.
Some settings (e.g., security settings, domain rules) behave as if they are stored on Bitwarden’s servers – they are always persistent across logins and browsers.
Other settings are apparently stored in cookies. For example, the vault timeout options will be persistent across logins and browsers, unless cookies are cleared, or you saved changes while in an incognito/private window (which automatically deletes cookies when the browser is closed). Edit: Vault timeout options are remembered between logins within the same incognito browsing session, if and only if the incognito browser was open while changes were made in the non-incognito browser).
However, the Account Setting Preferences other than vault timeout options (e.g., language, icons, gravatars, etc.) are a bit of a mystery. If using a regular browser (not incognito/private), the settings are remembered between logins, but if using an incognito/private browser, the settings do not persist – thus, these settings behave as if they are stored in cookies. However, unlike the vault timeout options, if I make a change in a regular browser (not incognito/private, to allow the cookies to be saved), then the preference settings do not load when subsequently logging in on an incognito/private browser (Edit: even if the incognito browser had remained open) – only the vault timeout options are recovered in the incognito browser. This is odd, because although I’m no expert on cookies, my experience is that incognito browsers do load any available cookie information (saved by a regular browser) – Edit: if the incognito browser had been open while the cookies were set by a regular browser – but they do not save their own cookies.
The last used settings on the password generator behave in a similar way to the account preferences described in the previous paragraph. There may be some additional oddities in the behavior of the password generator across incognito and non-incognito browsers, but I’d have to do more testing.
It would be nice if all settings were stored in a way that they would always be persistent.