On the uSync dashboard there is a settings tab.
This will show you the current settings for uSync on your site.
For Umbraco 10 (and asp.net core in general) settings are stored in the appsettings.json file or any one of the other possible settings locations available as part of [https://docs.microsoft.com/en-us/aspnet/core/fundamentals/configuration/?view=aspnetcore-6.0)(Configuration in Asp.Net core).
As such you cannot just write the settings back to disk, and be certain that the values you have set will be the ones used by the site. So the settings page will show you the settings and what you can enter in your appsettings.config file to change them.
For more details on what settings can be changed see our appsettings.config reference.