Many colostomates struggle with this particular problem and look for solutions that allows formed stool to drop into the pouch without getting stuck at or near the stoma. Ileostomates, generally speaking, have more liquid output because there is no colon to absorb the water from the waste as it moves through and out of the body.
One idea is to wear a filterless pouch and remove gas manually. Leaving a little air in the pouch may keep the pouch from sticking together at the top as warm air rises. Anotherl suggestion would be to drink more fluids and add more fruit to your diet.