I spent hours trying to install DDG. I tried all of the suggestions including - my last try for the night - making DDG my home page. It did not seem to work. But I think the problem was that my brain was starting to dribble out of my ears. In any case, when I fired up my desktop the next day and clicked on IE icon in my taskbar expecting to get the Time's bad news about - it grieves me to say it - President-Elect Trump, I was happily surprised that the page that opened was DuckDuckGo. For what it is worth, I have a HP 110 Desktop with an AMD A4-5000 APU processor running Win 7 Home Premium 64-bit and IE 11.
I would like to suggest that when the home page is the means of access to DDG, there be some way deleting the invitation to install DDG. It doesn't hurt anything to leave it up, it is just a tiny bit of clutter that needn't be there.
By the way, when I tried the more conventional routes for installing DDG, after the first try I got the message that DDG was already installed. However, neither the search below the Start button nor Windows Explorer would come up with DDG and it was never listed among my programs.