Paytm wallet is a secure and RBI-approved digital/mobile wallet that can meet almost all your financial needs. You Can use the Paytm wallet outside India to transact with Indian merchants, like mobile payments, and DTH recharge. 

Short Direction: {Amazcart> Dashboard> Payment Gateways> PayTM> PayTM Environment> Merchant ID> Merchant Website> Merchant Key> PayTM Channel> PayTM Indrustry Type> Gateway Logo> Update.}

This is a unique identifier provided by Paytm to every merchant. Merchant Key is a unique secret key to secure every request's encryption. This must be kept on the server side and should not be shared with anyone. 

1- PayTM

2- PayTM Environment

3- Merchant ID

4- Merchant Website

5- Merchant Key

6- PayTM Channel

7- PayTM Industry Type

8- Gateway Logo

9- Update it.