How to change the ADMIN image in mobile view?
You may change the default ADMIN user in mobile to any image by using your own image URL.

.admin .user-image,
.admin .message-user-image {
background-image: url("//rumbletalk-images-upload.s3.amazonaws.com/cc244d13c0e7e7bb6c4b63830314dc61/1444667334-usericon-white.png");
}