This guide will let you know how to Change Emblem & Calling Card in Call Of Duty Modern Warfare 2.
First, you have to press the options button and go to your level or your profile using the r1 button. After that, click on the edit calling card and it will show you all the cards that you have collected. You can select a new one from this list by pressing the X on the card you want to use.
Now you have to go to your emblem by clicking on your profile and selecting Edit emblem. It will show you all the emblems that you have collected. You can choose a new emblem from your collections.
Now the last thing you have to do is to go back to your profile and select clan tags. A keyboard will appear in front of you showing your clan tag, you can change it by typing the new tag and then saving it.