Leave them at default. If your confident that your system will work with all of your devices well on 40Mhz only, then you can change this.
CTS has a new default of 64 which NG recommends using. Some users have experienced connection issues. So you can change this to 2347 to test to see if this resolves anything. WMM should always be enabled.
My Setup | ISP SparkLight | Internet Cable 1000↓/50↑ CAX30 Mode Mode | Wifi Router XR500 and RBK863 Router mode | Switches NG GS105/8, GS308v3, GS110MX and XS505M | Additional NG HW: C7800/CAX3/CAX80/CM1100/CM1200/CM2000, Orbi: CBK40, CBK752, RBK50, RBK853, RBK752, RBK953, SXK30 | NightHawk: MK63, R7000, R7800, R7960P, R8000, R8500, RAXE500, RAX120v2, RAX50v2, XR450/500/700/1000, EX7500/EX7700
