Mail issues

Ive recently set up my first MacBook and set up my hotmail email account but when I've read or deleted emails through my Macbook they are still saying unread on my iPhone, anyone any ideas how to sort this?

Sounds like your Hotmail account is set for pop3. The features you are looking for generally work best with IMAP accounts. Hotmail doesn't really play nice with IMAP this may be a good workaround. Hotmail Has IMAP And Works On iPhone | Sir Slur

Can you tell me how I can fix it?

Everything I have read says that the directions I linked to in that article fixes the problem for most users. Try following the steps in that article. When you get to Step 4 enlarge that picture and enter the information as it appears on that screen. Obviously enter your username and password other than that author's password.

I personally have not tried this since I don't remember ever having a Hotmail account