In Yellowfin 6.3 and later there is a configuration option called "Login autocomplete". When set to "Off" (the default value), this option stops browsers from remembering passwords typed into the login screen, even if the end user has enabled the option to save passwords in their browser.
This behaviour is no longer supported by the current releases of all major browsers, and as such will be removed in the next Yellowfin patch. From now on, if you need to stop browsers remembering login passwords, this will have to be configured at the browser level.
Because the behaviour is no longer supported in the browser, there is no way for Yellowfin to work around this. Additionally, the behavior is generally considered to be undesirable from a security point of view.
Please see the following links for information about different browsers' removal of support for this behaviour:
Essentially, you need to remove the following line from your custom page:
‘if (vm.getAutoCompleteOption()) autoComplete = "on";’