Some Activity Statement fields are pre-filled with information from the ATO, or from Essentials.
If the value is pre-filled from Essentials, the label at the end of the field shows Essentials. If you change the amount in one of these fields, the label changes to Adjustment. You can change back to the pre-filled value at any time by selecting Essentials from the drop-down at the end of the field.
Make sure to click Save at the top of the page to save the return to your practice database and set its status to In progress. That way, you'll be able to find the return on the Tax page.