This may seem like a small thing to write about, however I have lost count of the number of times I’ve had this discussion with different stakeholders – how do we refer to the ‘things’ that ‘belong’ to the user inside a user interface?
- Is it ‘My documents’ or ‘Your documents’
- Is it ‘My personal details’ or ‘Your personal details’
- Is it ‘My orders’ or ‘Your orders'
Well it is time to lay this one to rest, it should be ‘your’—your documents, your personal details, your orders.
And here are a few reasons why.
1. Greetings
User interfaces often greet us, particularly if we log in. We often see phrases in user interfaces such as ‘Welcome John Smith’ or ‘Hello John’. Receiving this simple greeting indicates that the device, service or brand is talking to us and therefore has an identity or persona of its own. Therefore any use of the word ‘My’ would refer to that persona and not to the person using the product.
It sounds quite strange but just read these two phrases
- Welcome John, here are my documents
- Welcome John, here are your documents
Which makes most sense?
2. Tone of voice
When designing user interfaces UX designers often refer to ‘tone of voice’. By discussing ‘tone of voice’ we are trying to formulate how the brand should ‘talk’ to the user via the product. Again we are indicating that the user interface has its own identity and talks to the user (or that the brand is using the user interface as a channel to talk to the user). As the user interface is talking to you, it should talk to you about your things—your documents, your personal details and your orders. 
3. User interfaces literally talk to us
So the two previous points are about how user interfaces appear to talk to us. However some user interfaces actually talk to us. Siri on iPhone is probably the best example of this. Siri has a name, has a personality and even tells jokes. Wouldn’t it be weird if she referred to ‘my appointments’ or ‘my emails’ rather than ‘your appointments’ and ‘your emails’?
So use ‘your’. It just makes more sense.