Transaction approval must be enabled for your sales and purchase transactions separately.
Enable Sales Approvals
To enable transaction approval for sales transactions (Invoices, Estimates, Sales Orders and Credit Notes):
Enable Purchase Approval
To enable transaction approval for purchase transactions (Bills, Purchase Orders and Vendor Credits):
You can also choose to set up a multi-level approval process for the transactions that should be approved by two or more people. To configure a multi-level approval process:
Note: You can add up to 10 approvers.
and GST filing.