1. Go To Preferences From Option.
2. Click On Connection.
3. Go to Bandwidth.
4. Go to BitTorrent.
5. Open Queueing And Set The Value As Shown Below.
6. Now Click on Advanced option and search for net.max_halfopen and set its value to 90. Click On Apply
7. And Press Ok Now Go On main Page of Utorrent , right click on your downloading file and select Bandwidth Allocation then High.