I'll still post mine after for you, but you might want to try changing your targeting as well as I don't personally see any need to keep your healing target selected all the time. What I do at the start of a boss is immediately focus target it, so you always can see what it is doing. Then you just use the D-Pad up and down to cycle your healing targets, and then if you hold down R2 and press L1, or hold L2 and press R1 it will always cycle the enemies, typically always selecting the boss first. I found this works for me, do that to target the boss, do some DPS, press up and down to select the party and heal.