Nighthawk mr1100 with external antenna??? Help

Have a Nighthawk mr1100 mobile hot spot router...just hooked up about a week ago. With moving the router around the house, the best speed i can achieve is around 40mbps download(showing 2 to 3 bars of reception on routers digital interface). This is up greatly from previous centurylink provider so happy with that. Would like to optimize and maximize the reception. Is there a way to achieve more bars of reception in order to increase speed? I purchased a dual antenna external antenna...hooked it up, moved antenna about 5 feet away from each other. Speed and reception did not really improve. Do I need to go into the settings of the router and change something to get it to recognize the antenna? I'm not very tech savvy so any helpful advice is appreciated!