Hi,
The default settings are the best for the general case. If you have a specific setup (like few images) then you could improve the results by adjusting the parameters. Without any information on your configuration and without seeing any image, it is not possible to provide advice.
High or Ultra on feature extraction is not a guarantee to get better results. It may even decrease the results in some configurations as extracting more points can make it more difficult/ambiguous to match them with other images.
Best,
Fabien