Step 1

From the menu bar, click Tool, click Re-Login. 

Step 2

Press the Chg. PW button to display the dialog box for changing the password. 

Step 3

Enter three passwords: the current password in the first field and the new one in the other two. 

Step 4

Press the OK button to update the password. 

What if you don't remember your password?

You have the option of using [SHIFT] + [↓] to bypass the password screen, then going to tool, and re-log in to change it.
If you want to use a password, you could always uninstall, then reinstall Wincaps.