For all people that are struggling with uploading avatar images, it turns out that (I may be wrong but I tested thoroughly) the avatar image only accepts the exact image name "profile.png". It cannot be .jpg file, it cannot be something like "profileee.png". So in order to upload your avatar image correctly, you need to upload an image and rename it to "profile.png" (replace the existing one). Also, ensure that the image size is less than 1MB.