SSL Certificate Considerations
By default, Passwordstate comes installed with a Self-Signed Certificate as this is the only type of certificate Click Studios can supply during the installation.
Typically, you would change your certificate to something more secure such as one issued from your Internal Certificate Authority, or a purchased one from an online provider.
If you have your own SSL certificate installed on the web server you’d prefer to use, you can modify the bindings for the site in IIS, and select the appropriate certificate.
If you wish to continue using the self-signed SSL certificate, then you may want to instruct your users to “Install” the certificate on their computer, so the various Internet browsers don’t complain about the certificate not being issued by a trusted authority.
To install the certificate, you can follow these steps below. You will effectively be exporting the certificate and reimporting it into your Trusted Root store on your machine. The example below uses Google Chrome as the browser, but you can achieve the same thing in other browsers.
Using Chrome, browse to your Passwordstate website and you should see a screenshot with an error saying NET:ERR_CERT_AUTHORITY_INVALID

Click on the Not Secure button, and then click on the Show Certificate button:

Under the Details tab, click Copy to File…

Run through the Certificate Export Wizard, leaving all default options. During the process, set a name for your certificate (which can be anything), and save it to disk.
Now go to Start -> Run and type in certlm.msc and hit enter. This opens up the Local Computer Certificate Store on your computer.
Expand out Trusted Root Certificate Authorities and right click Certificates, and choose All Tasks -> Import:

Now run through the import process, using all default options, and browse to the certificate you saved to disk in the step above. Once this completes, you will see a Successful Import message.
You can now restart your browser and try browsing to your Passwordstate URL again, and you will no longer see the Browser Warning about the certificate.
Note: For an in-depth explanation of the different types of certificates you can use on your Passwordstate website, please see this KB Article: Passwordstate Certificates Explained