OK, starting like this from the command line worked…
redshift -l LAT:LON
This seemed to work if you use your actual LAT & LON
Alter screen temp (whatever that means) manually
redshift -O 4500K
I found that command by typing
redshift -h
however typing the following, doesn’t undo the above (it appears to stay the same)
redshift -O 6500K
In addition repeating the 1st command seems to have a cumulative effect… screen gets redder!
The only way I found to revert back is to logoff/logon.