I'll be more than happy to help you turn off spell-check in your QuickBooks.
1. Go to the Edit menu.
2. Select Preferences, then click Spelling.
3. Under My Preferences window, unchecked Always check spelling.
4. Click OK.
When adding another language in your QuickBooks, we'll have to change the Region and Language settings of your computer. This way, we'll be able to have your timesheets and invoices displayed in Italian characters. I'll guide you how:
Click the Start button, and then type in Control Panel.
Choose Clock, Language, and Region, then click Change Location.
In Home Location, select Italy.
On the Administrative tab, select Change System Locale, then choose Italy.
Select Apply, then click OK.
Reboot the computer.
Re-open your QuickBooks and check if your timesheets and invoice are already in Italian characters.