Select or modify units in OpenFOAM is totally different compared to ANSYS CFX or ANSYS FLUENT, in OpenFOAM it is necessary to use a table and know the position of the exponents to know the unit of the variable.
Units in ANSYS CFX
Units in ANSYS FLUENT
In ANSYS FLUENT you quickly customize any unit of any variable
Units in OpenFOAM
In OpenFOAM I recommend watching the video
Please watch this video for a better understanding.