Ok first, ignore what sic asked. It makes zero sense.
Second, you mention you eat and eat but don't gain anything, wrong. You're a liar. Before you get upset realize I know what im talking about and im feeling nice enough to shed some light on the topic.
In order to gain strength and weight without getting chubby you need to eat the right foods and lift heavy weights. You need to fill your face with MILK, whole grain breads, whole wheat pasta, brown rice, veggies, some berries/bananas w/e, and lots of lean meat. Think its easy? We'll its not because you will be eating clean as hell and need to hit approx 2,500-3,500 cals a day. A can of tuna is what 150 cals?
Now that you're eating the right foods you need to perform the proper lifts in the gym to turn those pencil arms into something impressive. Three days at the gym for heavy lifting no more. Monday, Wednesday, Friday.. the other days of the week are there for resting and if you want cardio. (Stair climbing, Burpees, Sprints, Jump Rope) Stop running! No need!
Monday - Squat + Whatever leg exercises you want
Wednesday - Bench, Overhead Press, Dips, Tricep Variation
Friday - Deadlift, Bent Over Rows, Chins, Bicep Variation
Trust me, i've tried the whole body building crap before nothing works better for gaining strength than a powerlifting routine, milk (can't stress it enough) and food.