Cannot restore to original setting after reset param to default

I had an error message (attached) downloading the DF log (Log setting values is also attached), so I took the advise from the forum to press the “Reset to default” button in Full param list. Before I did that, I save the original setting to a file. After Reset the param to default, the problem still can’t be solved… still error message in downloading DF log.

Now another problem comes up :-- After I restore the param to original setting by pressing the “Load from file” button in Config page to load the saved file back, the settings are still at default values, and original settings cannot be restored. Also what is the use of the “Load Presaved” button. This is not explained in Wiki.

Revo running arduplane 4.0.5, MP 1.3.74
Thank you for any help in advance.