My "sent" email now only shows my first name as the sender

Are you seeing your full name under the following:

iCloud.com Mail Client:

1. Open icloud.com in browser

2. Select Mail

3. Click gear icon in top right corner

4. Select Preferences

5. Select Accounts Tab

6. Should see a Full Name field on that screen

As per you instructions , click on the drop down arrows in the top right corner .

Click on gear icon .

The first and last name appears , fine but where is the edit button , what op is asking - My "sent" email now only shows my first name as the sender. Until recently it showed by full name--first and last--as sender. I prefer that. How can I reset my sender name?

So how to reset the first and last name please post back .

Enter www.icloud.com with apple id and password , in contacts section select the contact , click on edit .

Enter the last name in the field and click on done to save .

There is a Preferences, it's the first option.