Welcome to the forums formdev1,
To start, the placeholder attribute does not have very good browser support,
62.24% to be exact.
http://caniuse.com/input-placeholder
Secondly, that is the natural functionality of the placeholder attribute,
it disappears when you start entering text rather than onfocus.
If you are looking to accomplish a placeholder that is
cross-browser, you can use JavaScript (or jQuery) instead.
Code:
<input type="text" name="fname" size="25" placeholder="Username" onfocus="this.placeholder = ''" onblur="this.placeholder = 'Username'" />
All the best,
Sammy12