You already know that if a customer has added a product to their cart and decided to change the quantity, the only way the order can be reflected with that change is by clicking on the update cart button. But that’s just another step for a customer. And they probably want to see what that new total is.
Auto Update Cart for WooCommerce
A simple extension does this one thing. You set it and it’s good to go—no having to go back and reconfigure it.
Once installed, you will find a single setting for the extension under Settings > Advanced > Auto update cart. And controls the time delay for when a customer makes a quantity change and when the cart updates.
Without this plugin when I update the cart, I would need to click the update cart button manually.
With the extension activated and the time delay set at one second, there is no need to hit the update cart button.
Note: depending on what you set your time delay at, if the customer manually updates before it auto-updates, that will work as well.
More Ways to Control Quantity