Biological process

positive regulation of UDP-glucose-glycogen glucosyltransferase activity, positive regulation of UDP-glucose:glycogen 4-alpha-D-glucosyltransferase activity, positive regulation of UDP-glycogen synthase activity, positive regulation of UDPG-glycogen synthetase activity, positive regulation of UDPG-glycogen transglucosylase activity, positive regulation of UDPglucose:glycogen 4-alpha-D-glucosyltransferase activity, positive regulation of glycogen (starch) synthetase activity, positive regulation of uridine diphosphoglucose-glycogen glucosyltransferase activity

Any process that activates or increases the frequency, rate or extent of glycogen (starch) synthase activity.