In general, the 7000SXT backwash filter programming is just fine as the default. The only thing you would need to program is the backwash frequency. This is done by pushing and hold the up and down arrow buttons for about 8 seconds. This will get you into low level programming.
DO is the regeneration frequency. For a Carbon tank in most applications, every 7-30 days is just fine. For an iron removal system, more often, every day to every 5 days depending on many variables.
RT is regeneration time, leave at 2:00
Let me know if you need more information.
here is the service manual which includes full programming.