You still have some wiggle room with the TA, so I'd bring the pH down first. Your pool info isn't listed in your sig which might help us, but if you have any sources of aeration such as bubblers, spillway, waterfall, SWG, remember those also contribute to pH increase.
Just like chlorine, muriatic acid is a regular meal on any pool's diet - just not as much. Ideally we try to adjust pH and TA together in hopes to reduce how fast pH rises. New pools really struggle because of plaster curing. But yes, all those other features will drive it up over time, so having a gallon on-hand to keep pH from going over 7.8 (preventing scale) is always good. Remember, some pools like a pH that settles in the mid-7s, while others seem to remain steady on the high end of 7.7-7.8. In time you should find that "happy place" for your pool as well so that pH and TA don't seem to bounce up & down so often. Have a nice weekend.