It is very difficult to keep up with head positioning. The struggle is real, babies necks are not strong, so their head will turn to either the left or the right. The problem is they will have a flat head on the side they prefer, sometimes both sides and even the back or the head, this is called plagiocephaly. Along with this, sometimes torticollis is noted, which is tightening of the neck.
So what do you do? The first thing is prevention, tummy time is the best thing. Three times a day, if you can do at least 10 min each session. The best time is before a feed, when the baby starts to wake a little, it's the perfect time to place them on their tummy and put them in that tucked position. The arms should be out from under them, elbows bent and hands out, one by their face and the other at the back of the head. The hips and legs should be in a tucked position underneath them with the back in a curved position. Don't let the hips frog out. This is a great time to give them a paci or fingers to mouth to work on their suck pattern before a feed. Tummy time should be on a flat, firm surface and babies should not be left unattended at this time. Another way to do tummy time is to place baby on your chest while you are in an upright position and leaning back a little. It is a great way to snuggle and babies will try and look up at you. As babies get bigger, they will try and lift their head. All this helps with strengthening the neck and torso.
Babies should be on their backs for sleep, sometimes babies will get a flattening on the back of the head, you can alternate head position right side and then left with each nap time. Remember for feedings, you can change your holding position so they are not always turned the same way. You can also change head of bed position in the crib or bassinet. If the bassinet is at your bedside, you can alternate the head of the bed as they will always turn to your voice. All of this will help with reducing head flattening and neck tightness.
Play time on their back on the floor mat where they can look straight up at the activity set is also a great way to keep their head moving and keep their neck from getting tight. So what if you notice that your baby is getting a preference to turning his/her head. Keep doing all the above activities and instead of alternating, keep baby with the non preferred side as a head position with feeding time, nap time and head of bed. Do this for a day or two and then reevaluate and if it is helping then you can go back to alternating accordingly.
Take the time to speak to your pediatrician and address your concerns. They may also want you to get a physical therapy, occupational therapy and be evaluated for a helmet.