I've got a download going, on UltraHigh priority, that has 45 seeds available but Tixati is only connection to 15 of them. How do I get the program to connect to all of them and increase my download speed?

There are two ways to get to max peers but if you are only concerned about one torrent... Transfers tab then choose options in the lower tabs then choose peers. Find max peers and increase that number. Sometimes the 45 seeds reported may not connect still and even if they do they may not send to you.