I would differ on any blanket statements about alternating FF and nasal masks. Some PALS do well 24/7 on one or the other. As regular readers know, I'm partial to the Circadiance "parachute-like" one because of its low weight and ability to use narrower tubing for less pull. Pull can significantly affect sleep quality.
I do agree with paper or nylon tape on the nose bridge if a mask is rubbing, but would also advise to really look at fit and other masks because there are more options than there used to be and some masks do not touch the nose bridge at all. Like anything else, nose bridges differ than we might think. Cpap.com offers free 30-day returns on many masks.
Cleaning the face and mask before applying is also a big help, which calls for having extras to swap out if someone is BiPAP-dependent.
Kathy, that much coughing suggests the possibility of target volume, IPAP max, and/or PS max being set too high, which is very common from the jump, so I'd be happy to help you dial those down and titrate back up. Also, just confirming that you are using a heated humidifier with distilled water?