What do I uncheck in the browser cleaner to prevent all my memorized sign in data from being erased?
For each browser where you want the details saving uncheck "Saved Passwords" and you may also need to uncheck "Saved Form Information".
That's because some websites save your login information as a form rather than just a name/password.
Also bear in mind that some websites, especially those dealing with money, paying bill, etc. may not allow the password to be auto-entered by your browser.
As a security measure you have to type it in each time.