If the ODBCINI environment variable is set to a release-independent odbc.ini file, then the application will be using the active TTU version of the driver. If the desired driver version is not the active TTU version, then you must either make the desired version the active TTU or set the ODBCINI environment variable to an odbc.ini inside the desired version's directory. See example below:
export ODBCINI=/opt/Teradata/client/16.20/odbc_32/odbc.ini