HTML editor is changing the code tags making them show on live page
Within the source code area of my HTML editor (was set up as iRite years ago), I am pasting an embed code for a youtube video, clicking the source button again to see the video embedded, saving the update to the page and all is good. If I then go back to edit the page to add further text or images below the embedded video, all of my code that I had pasted is now visible in the editor window, and if I click to view source, the greater than/less than characters of the code have changed to < and >
What have I done wrong ;) ?