Hello there, @kitoq.

At this time, the option to change the language to Spanish is unavailable in QuickBooks.

However, you can use the language settings of the browser to edit the one you're currently using. Let me guide you how:

1. At the upper-right of the opened browser, click the vertically lined dots. 
2. Select Settings.
3. Click Advanced and then Languages. 
4. From the Language drop-down, click Add languages. 
5. Select the language we'll want to use. Then, click Add. 
6. Click the three vertical dots beside the language.
7. Check the Display Goggle Chrome in this language box. 

I'll personally send this option to our engineers so we'll have the option to change languages within QuickBooks. 

Then in case you need to learn some tips or best practices in managing your QBO account, you can always drop by into our Help articles page anytime.

You're always welcome to post here anytime you need help. I'm happy to work with you. Have a great day!