Hi It may be the case that you have stored passwords in Firefox for Android for sites that you visit using the browser (for example; your email service provider). The master password is designed as a control to stop anyone who has access to your device from accessing your accounts online. You can read all about how the Master Password works in this [https://support.mozilla.org/en-US/kb/using-master-password-firefox-android article]. I hope this helps, but if not, please come back here and we can look into a different solution for you.