Welcome to Geeks to Go.
Am pretty new to all this stuff myself, but I have recently installed Windows 7 on my desktop myself, plus Windows 10 on my notebook - and I can tell you that I was pretty stunned at how easy it was to do! I am sure that many more people would do these things themselves if they realised how easy it is!
I am not really clear whether or not you are saying that your new OS seems to be working okay. If so, then all will hopefully be fine.
Not sure what you mean about going to the boot screen. In order to get your installation to run from the usb drive, you would have had to ensure that the boot order was set up to boot from cd/usb first - but if the installation ran okay you don't have to worry about that unless you want to change it back to boot from the hard drive first.
I hope this has answered your question. If not, please let us know.
EDIT I assumed above that as well as reformatting, you were talking about installing (or re-installing) Windows 8.1. You only mentioned the reformat, but it would have presumably have just been part of the installation process.
Edited by Channeal, 10 July 2017 - 07:46 AM.