By default, the grid csv data export will use a comma as the field separator unless the job decimal format is set to 'I' or 'J', in which case a semi colon will be used.
This value can be set to a character which will be used instead of the above. This can be used to override the default behavior, or to use a different character entirely.
Example:
pui["csv separator"] = ",";
Where do you save this configuration option? Here.