First of all, as @scorza420 mentioned, it’s a good idea to place the wallet shortcodes in a page that is only viewable by your members.
However, even if you don’t do this, it should not be possible to see user-specific data such as balances or deposit addresses when you are logged out. If you are seeing this info when logged out, it indicates a problem with your server cache.
If you instead see actual coin information, you should whitelist the plugin’s JSON-API in your server-side cache plugin(s). This could be “W3 Total Cache”, “WP Super Cache”, “WP-Optimize”, or some other plugin. You can exclude all URLs that have the _wallets_action GET parameter.
Please let me know if you continue to face this issue.