How to configure Diagnostics tool for mscrm

I am trying to trace a job, and when I try to configure the PLATFORM TRACING the changes "aren't save" for example I change the - Maximum file size to 100MB from 10MB, and still all the files are created as 10MB I try to change the Directory but files aren't written in the new directory... after each change I clickl the save button the configuration is changed on the Diagnostics tool UI but it stays the same when I run the tool.
What am I missing?