How do I mark an expense as a depreciation?

Hello,

I have a number of expenses that I need to record as depreciation (mobile phone, laptop, etc. for purely professional use). I have already recorded the expenses as standard expenses. Under the depreciations section (behind the info button), it states that you can mark these expenses as investments. However, I cannot find this option. Can you tell me exactly how to do this?

Kind regards,

Murielle