I'm not sure what's happening with IE (I've never used it!) but having to sign on each time you visit the site may have been avoided earlier because you'd asked your browser to remember the password, and this was somehow not done once you had the new password.
To set your own password, click on the "My Account" link at the top right of any WP screen, then click on "Edit Profile".
Scroll down the screen a little and you'll see "Password" on the left, under all the other options.
Type in your new password into each box (so that the system can check you're not making a mistake with it) and then click on the "Save Profile Changes" button just below.
Log out, then log in again and provide the password you just entered. Depending on the browser you're using, it may ask if you want to remember the password so choosing that will hopefully resolve the situation where you're being asked for it every time.
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Giraffe: a ruminant with a view.