I believe a token is stored in a cookie for the second factor in the two-factor authentication, so if you clear cookies for Airbnb between visits, that would explain the problem. Note that in private windows, all cookies are temporary, so you cannot use a private browsing window and avoid this problem. I will assume a regular window. There are several ways that cookies might be cleared... '''(1) If Firefox may be set to only allow session cookies for the site, once your session ends, that cookie is cleared''' You could have set this either as your default (Preferences > Privacy > Keep until: I close Firefox) or for the specific site. If you prefer this setting, you can make a site exception. The easiest way is next time you are on the login page: (A) Set "Allow" permission for Set Cookies on the Permissions panel of the Page Info dialog (details below) (B) Clear existing cookies (since they are session only cookies) (details below) (C) Reload the page and log in '''(2) Firefox may be set to clear all cookies at shutdown''' This is an option some users set on Preferences > Privacy with "Firefox will: Use custom settings for history". To the right of "Clear history when Firefox closes" -- if checked -- a "Settings" button will be available to select categories of data to be cleared. Uncheck cookies, and also do not clear "Site Preferences" since that will remove your site-specific cookie permission. '''(3) An extension may be modifying how Firefox handles cookies''' Do you have any cookie-related or privacy-related add-ons? I'll mention how to check that further down. '''(4) An external program may be "cleaning" your browser data''' You can disable these features in your security/privacy/cleaning software. ---- You can call up the Permissions panel of the Page Info dialogusing any of these: * right-click (on Mac: Ctrl+click) a blank area of the page and choose View Page Info > Permissions * (menu bar) Tools menu > Page Info > Permissions * click the padlock or "i" icon to the left of the site address, then the ">" icon, then More Information > Permissions Scroll down to "Set Cookies" and uncheck the "Use default" box, and then select the permission you prefer. Then switch over to the Security panel and click the View Cookies button. In the dialog that opens, airbnb.com should be pre-filled in the search box at the top of the dialog so you can remove that site's cookies individually. After finishing that, close out of Page Info and reload the page -- use Command+Shift+r to bypass the cache and get a full set of fresh files. Hopefully now the second factor cookie will be retained long term. ---- You can view, disable, and often remove unwanted or unknown extensions on the Add-ons page. Either: * Command+Shift+a (Windows: Ctrl+Shift+a) * "3-bar" menu button (or Tools menu) > Add-ons * type or paste '''about:addons''' in the address bar and press Enter/Return In the left column of the Add-ons page, click Extensions. Then cast a critical eye over the list on the right side. Any extensions that Firefox installs on its own are hidden from this page, so everything listed here is your choice (and your responsibility) to manage. Anything that looks as though it could affect cookies? If in doubt, try the "More" link or Preferences button for more information, or click Disable to test whether it's having any effect. Sometimes a link will appear an extension you click to Disable indicating you need to restart Firefox before the change takes effect. You can complete your work on the tab and click the link provided for that as the last step. Any improvement?

Thank you very much!