My defaults for FT8 on my Yaesu FT-891

I have found various pages and videos on the settings for FT8 on the FT-891, but none that really scratch the surface of what needs to be turned on or off. So here's what I have figured out on my own. WSJT-X and the cat programs that are utilized by WSJT-X DO NOT send these commands for you. It's up to you the operator to set these parameters in the radio ahead of time. You can send these commands from the CMDline. With a little adjustment you can also create a batch file to do your bidding. Make sure you're not accessing the COM port before issuing these commands or you'll get an access denied error.

The EX CAT commands are menu functions.  There might be menu functions for the rest, but not easily identified in the CAT manual. The 4 numbers after the EX is the menu location.

Description CAT Command Notes
Auto Notch (OFF) BC00;  
Clarifier (OFF) CF000;  
AGC Function (OFF) GT01;  
IF-Shift (OFF) IS00;  
Keypad Lock (OFF) LK0;  
Operating Mode (DATA-USB) MD0C;  
Monitor Level (OFF) ML000;  
Meter Display (SWR) MS3; This is just preference, I like to see the SWR in case my Ariel gets tangled up in something and I don't see it right away. I will see it on the display.
Narrow (OFF) NA00;  
Noise Blanker (OFF) NB00;  
Noise Reduction (OFF) NR00;  
Preamp (IPO) PA00; Intercept Point Optimization just works better for me. PA01; (Pre-Amp) could work better for you
Power Control (5 Watts) PC005; Set low for QRP, but can be anything up to 100.
RF Attenuator (OFF) RA00;  
RF Gain (Max 30) RG0030;  
Band Width (3000) SH0117;  
Squelch Level (0) SQ0000;  
Data Mode (OTHERS) EX08011;  
Data Lower Cutoff Frequency (OFF) EX080500;  
Data High Cutoff Frequency (OFF) EX080700;  
Data PTT Select (DAKY) EX08100;  
RTTY Lower Cutoff Frequency (OFF) EX100100;  
RTTY High Cutoff Frequency (OFF) EX100300;  
Data Gain (50) EX1614050; This is the default level
RTTY Output Level (50) EX1008050; This is the default level
DATA Output Level (50) EX0811050; This is the default level. On the Signalink your receive dial will be at 9 O'clock provided your input(MIC SIDE) is set to 100%
DATA In Select (BACK) EX08091; This might might not be necessary as Operating Mode DATA-USB(MD0C;) does the same thing.