Usually it would be CV 29. On most all decoders adding “1” to whatever the value is in CV 29 (so like if it’s currently “18”, changing it to “19”) should reverse the direction of travel.
Stix has you covered! Just note - if you read back CV 29 and it’s already set to an odd value (eg: 35), then subtract one, and set CV 29 to that.
If that loco has an 8-pin NMRA connector for the decoder, it’s also possible they plugged it in backwards when (re)assembling it for you. I’d be suspicious of that if CV 29 is already an even value, but the loco is running backwards.
“Configuration Register 1” I guess is Bachmanns name for CV29, But the important thing to know is that CV29 is standard in all DCC decoders. Each of the 8 bits controls a specific setting. A value of “6” would mean that the decoder is in short address (default=3) 28/128 speed step mode, with dc operation enabled. S value of “7” is the same thing, with reversed operating direction.
Calling it Configuration Register 1 is a reference to the earliest days of DCC when you programmed decoders in Register mode, also called Physical mode. There were only 8 registers defined, as early decoders had limited memoery and function. However, the equivalent of CV29 was Register 5. Register 1 was the equivalent of CV 1, the short address.
There is no register 5 on the list. CV 1 shows primary address as the discription and the one next to CV 29 is the register 1. On the list CV 29 is showing a setting of 6.
If this is the reading I get on CV 29 should I go to a setting of 5 to change it’s direction
If the number in CV29 is even, then you want to make it the next HIGHEST odd number to change direction (simply add 1). If the number is already odd, you subtract one - make it the next LOWEST even number.