WHMCS doesn't have an integrated feature to automatically update exchange rates. Instead, it relies on the rates you manually input in the currency settings. To update exchange rates manually in WHMCS, follow these steps:

1. Log into WHMCS: Access your WHMCS admin panel using your username and password.

2. Navigate to Configuration: Click on the "Configuration" tab in the top navigation menu.

3. Currency Settings: Under the "System Settings" section, click on "Currencies".

4. Edit Currency: Locate the currency you want to update and click the "Edit" icon (pencil icon) next to it.

5. Update Exchange Rate: In the currency editing view, you'll find an option to set the exchange rate. Update this field with the current exchange rate.

   For example, if you're using USD as your base currency and you want to set the exchange rate for EUR, you'll input the equivalent value of 1 USD in EUR.

6. Save Changes: After updating the exchange rate, click the "Save Changes" button.

7. Repeat for Other Currencies (if needed): If you have multiple currencies, repeat the above steps for each one.

Please note that if you're using a payment gateway that automatically handles currency conversion during transactions (e.g., PayPal), the exchange rate from the gateway may override the manually set rate.

If you want to automate the process of updating exchange rates, you'll need to implement a custom solution that periodically fetches and updates the rates from a reliable currency exchange API. This typically involves writing a script, setting up a cron job to run it at regular intervals, and updating the rates in your WHMCS database. Keep in mind that automated exchange rate updates might require programming knowledge.