After you've shared a read-only board, there are some additional settings you can modify to add a password, set a welcome message, and embed your board.

You can change the password on your board by clicking on the Share button at the top right and looking for the "Require a password" field.

Click on the "Change" link, and enter your new password.

Now, anyone who attempts to visit your board using the shared URL will want to enter that new password to gain access.

To edit or remove the welcome message from your "read-only" board, click on the "Share" button in the top right of your board. This will open a window showing all available options.

To turn off the welcome message entirely, just click on the "Set a welcome message" switch:

To update the message, just change the text as it appears in the "Set a welcome message" field, and it will save automatically.

You can create an HTML embed of your board in the board's Share menu. Just use the toggle next to the "Generate HTML embed code" option after you've enabled a read-only link:

At the moment, this can only be a read-only view of a board.