Hello, have you used JQuery? see how easy it is to solve your problem with it.
<html>
<head>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.1.0/jquery.min.js"></script><script>$(function(){$('input').val('')})</script></head><body><form><inputtype="password" value="123" placeholder="digite sua senha" autocomplete="off" />
<input type="text" value="oie" placeholder="digite um texto" autocomplete="off" />
</form>
</body>
</html>
In the example I used, every time you load / open the page the fields will be cleaned, you can adapt the code as you want.
The Placeholder = is to inform something in the field for the user to read
Autocomplete = is to activate or not the list of information already entered in the field
I hope I have helped