You can prevent technicians from making changes to invoices that have already been approved.
On the Company tab, click Invoice Types, and then on the Invoice Types page, click Edit next to the appropriate invoice type.
In the Invoice Type dialog box, select the Customer Approval Required check box, select the Block Editing After Approval check box, and then click OK.
Ask your team to update the main database on their mobile devices.
If the Block Editing After Approval check box is selected for an invoice type, you cannot edit invoices of this type after they have been approved (for example, if an approved invoice was changed to Draft in Back Office, the Edit action will not be available).