Unread emails are bold. To open a message, simply click it in your message list.
By default, replies to emails are grouped into conversations. It may take some time to get used to conversation view, but keeping all the emails in a thread makes it easier to keep track of them and reduces inbox clutter.
However, if you prefer to separate all of your existing and future emails, you can unthread them:
In the top right, clickand select Settings.
In the General tab, scroll to Conversation View and select Conversation view off.
At the bottom, click .