Change Registration Text "Usernames can contain only letters, numbers, ., -, *, and @"

The text “Usernames can contain only letters, numbers, ., -, *, and @” shows when registering and some enters one of the things above. 1 thing is you can’t use Upper case letter and that is confusing my traffic since its not stated how can I change that text to “Usernames can contain only lower letters, numbers, ., -, *, and @”