I'll admit I often get bored looking at the same old pictures my friends have as their avatars in BlackBerry Messenger. Some just don't change them often (or at all like myself) or I just don't like the picture they choose. I also have my wife's BBM on my homescreen (as seen above) and like to change up the image from time to time. I had to dig a bit to get this done since I had tweaked a few settings, so take a read through this quick tutorial if you're looking to change things up a bit.
How to change a contact's picture (avatar) on BlackBerry Messenger
First off, go to your BlackBerry Messenger options and make sure you haven't checked Replace BlackBerry Contact Pictures With BlackBerry Messenger Pictures. If this is the case, it will actually do the reverse of what we want here and update the contacts in your address book with whatever they have chosen for their BlackBerry Messenger avatar.
After verifying in the step above, make sure the contact is listed in your address book (if not then add them). You'll also need to have them linked to your BBM contact list (in BBM, highlight the contact and select Link to BlackBerry Contact then choose the corresponding contact in your address book). Find them in your address book, press Menu > Edit. Move the cursor over the image in the upper left, and click on it. From here choose the image you'd like to display for the contact. When you have it choose Menu > Crop & Save.
Now go into your contact list in BlackBerry Messenger. Highlight the contact, Press Menu and choose View Contact Profile.
On this screen, next to Use BlackBerry Contacts Image choose Yes.
Press Menu > Save and you're done. Your contact will now show with the image you chose.