Anyone can tell me the command to up the threads for mining in the wallet?

its something you have to set in ROIcoin.conf file and its called genproclimit=4 ( only allows even nrs so 2,4,6,8 etc .. )
If you don't have a ROIcoin.conf , then make one in the same folder as your wallet.dat in %APPDATA%/Roaming/ROIcoin folder.