So recently I was upgraded to DC which is fine. However when I open a PDF document it opens a huge Internet Explorer window that takes up half of my screen, which makes me have to resize it. With the old Adobe Rader X once you resized the screen, and placed it where you wanted it stuck like that. However in DC you always have to resize it when opening a PDF using the Fast Web View that opens documents in an Internet explorer window.
Sorry for being late in answering your query.
Are you still experiencing this issue? If yes, please try following troubleshooting steps:
1- Reset Acrobat DC to its default settings using the steps given in this link: How to reset Acrobat Preference settings to default. reboot the machine after reset and try again.
2- If that doesn't work, repair Acrobat installation by clicking 'repair installation' under Help menu.
3- If the issue still persists, reset internet explorer settings using the steps given here: https://support.microsoft.com/en-in/help/17441/windows-internet-explorer-change-reset-sett ings (please note: customized settings for IE will lost once you reset IE).
4- Reboot the machine once and try again.
Feel free to update this discussion if you need any further help.