When AP data is converted up to version 8.1C, 3 sample filters are created for you. Integrity check rebuilds filters and colours.
Likely you did your first integrity check and the sample filter with red colour was applied (Balance outstanding > credit limit). If you don't want this, delete any or all of the sample filters. Then to reset the grid to all white, go to Maintenance / Apply Styles and click the 'clear unselected filter styles' checkbox, and the last blank row at the bottom of the grid. Then click the 'Apply' button to 'Clear all styles'.
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Regards,
Softrak Tech Support