From your Shopify admin, go to Settings > Payments.
In the Manual payment methods section, select pre-defined manual payment method called Cash on Delivery (COD)
Fill in the following fields
In Additional details, enter any information that you want shown next to the payment method in your checkout.
In Payment instructions, enter the instructions that you want your customer to follow to pay for the order. These instructions are shown on the order confirmation page after the customer completes their order.
Click Activate Cash on Delivery (COD).
Now, if the customer selects this payment method, it will automatically be saved as Cash on Delivery.
From your Shopify admin, go to Settings > Payments.
In the Manual payment methods section, select “Create custom payment method“ option
Fill in the following fields
In Custom payment method name, enter you custom COD name
In Additional details, enter any information that you want shown next to the payment method in your checkout.
In Payment instructions, enter the instructions that you want your customer to follow to pay for the order. These instructions are shown on the order confirmation page after the customer completes their order.
Click Activate payment method.
Go to Shipdock App → Settings → Cash on Delivery
Enter your custom Cash on delivery payment to “Custom payments methods” section
Now, if the customer selects this payment method, it will automatically be saved as Cash on Delivery.