BuddyPress allows its members to upload a custom avatar but WordPress doesn’t provides you any option to upload and use a custom avatar directly from your website, instead you have to use Gravatar.Com This is OK because provides you avatar that can be used globally in all WordPress sites simply by using your email address. But some site admins running a multi-user WordPress site face problems because they don’t get any option for uploading avatar image for the users who are not registered on Gravatar.Com
Now this problem is resolved, all you need is install and activate WP User Avatar plugin. This plugin allows you to use a custom profile avatar from Dashboard -> Users -> Your Profile page, simply visit this page then scroll down to WP User Avatar section and upload you avatar, you can your Media Library pictures also.
It also adds a new user avatar column showing custom avatars of users in Dashboard -> Users -> All Users page, the default user avatar column appears as it is, it doesn’t create any conflict with that so your users who have’t uploaded avatars on your website can continue using their default avatars or avatars from Gravatar.Com