The most relevant part is this: "NRML 738W OPTG IN 76ER N3DD OTS LAX" which basically means that the scheduled 738 aircraft [NRML 738W] will now be operating as a 763 [OPTG IN 76ER], because aircraft N3DD was found to be out of service [OTS] while in LAX
Despite the more common use of three character aircraft codes (763), most of AA's planning systems use four character codes (76ER) to account for the many unique configurations within an aircraft type
Can't remember what FTWDP means (think its the location and initials of the person making the entry) who in this case is named Petit...someone plz correct me if I am wrong about this part
Lastly, on top of the equipment change, your parents flight was 50 minutes late because they were awaiting crew [AWTG CREW]
Hope this helps...