Update GUIDE.md

GUIDE.md

@@ -26,7 +26,7 @@ Each client paired with the BitPay server requires a ECDSA key.  This key provid
 
 The private key should be stored in the client environment such that it cannot be compromised.  If your private key is compromised you should revoke the compromised client identity from the BitPay server and re-pair your client, see the [API tokens](https://bitpay.com/api-tokens) for more information.
 
-The [BitPay.Net Setup utility](https://github.com/bitpay/csharp-bitpay-client/releases/download/latest/BitPay.Net_Setup_utility.zip) helps to generate the private key, as well as a environment file formatted in JSON which contains all configuration requirements, that should be stored in the client local file system. It is not recommended to transmit the private key over any public or unsecure networks.
+The [BitPay.Net Setup utility](https://github.com/bitpay/csharp-bitpay-client/releases/download/v3.1.1912/BitPay.Net_Setup_utility_3.1.1912.zip) helps to generate the private key, as well as a environment file formatted in JSON which contains all configuration requirements, that should be stored in the client local file system. It is not recommended to transmit the private key over any public or unsecure networks.
 
 Follow the guide [BitPay.Net Setup utility guide](https://github.com/bitpay/csharp-bitpay-client/blob/master/BitPaySetup/README.md) that assist you to create the environment file which you will be able to modify it, either manually or by using the BitPay.Net Setup utility, later on by asking you to provide the path to your existing JSON file.