If you are using version 6.0 or earlier of the CMS, the content
editor and toolbar may not appear correctly in Internet Explorer 11 or
later. The issue does not manifest in later versions of the CMS.
Use either use a different browser such as Chrome or Firefox instead of IE.
Switch to IE10 mode in Internet Explorer. You can do this by pressing the F12 key to access the developer tools. Then select the emulation icon. Then update both "Document mode" and "User agent string" to IE10