You can change the ‘slope resistance‘ in the Tacx app in ‘settings’ .... or connect in Zwift as though you’re going to ride (so connect completely) and then from menu (on ride screen) go to settings and adjust the ‘trainer difficulty‘ slide to whatever percentage slope feel you’d like. My understanding is that the less slope difficulty you have, the easier (less gear changes but same watts required) uphill, but your ability to coast downhill is reduced by the same amount. Try playing around with it until you find a setting that suits - mine’s at about 50% for everything.