Several fields on the mobile device screens can be "locked". When a field is locked, it will retain the information you entered through subsequent transactions. This is useful if you are adding inventory to multiple items at one location or checking out multiple items to a single customer. To lock an individual field, enter the desired information, then click and hold on the field name. The field name will appear greyed out.
To unlock the fields, click and hold again. The fields will be enabled, allowing you to enter new information.