You can choose option "Background Download" when options comes when a list appears and you press download in UC Browser. In case of choosing "Regular Download" this problem occurs.
Hope you got your answer!
Update : For some pages Refresh or Clearing cache does not reset the zoom level. For those website click on the location bar and press Enter key or Left arrow that appears in the keyboard.
Clean the cache and cookie data in Edge. However it must not be necessary. Edge resets the zoom level to default when pressing refresh button.
The browser also "...
The answer to this question lies in the fact that Windows Phone Apps uses "isolated storage" to store anything on your device. So, if you have downloaded anything from any app be it UC Browser or Youtube Downloader, you can't access it other than from within that App. You can access the file downloaded through the "downloaded files" section in UC browser. ...
you may try UC Browser PC version.
its downloading function is more stable than phone.
also it can download videos from Facebook.
here's the link to the official website: http://pc.ucweb.com/?from=ghx0005