How to change your profile picture
If you want to change your profile picture, click on your current picture in the bottom left corner, then click on the gear icon in the popup that appears. This will take you to your Account settings.
After that, click on the Edit icon where you can see your name's initials or your current profile picture.
Here, you can select to upload a new profile picture or remove the current one. After you update your profile, all you have to do is click on "Save changes".
The picture you upload for your profile will be visible in the chat and in your email signatures.