It depends on what thresholds you are refering to. For example, default threshold for Slow page load or slow operation time is 8 seconds, but you have a lot of different thresholds (for database, SAP, HTTP, etc).
Those are configurable in the AMD. You can configure it doing the steps:
RUM Console -> Go to your AMD and "Open Configuration" -> Go to "Global" menu.
There you will be able to configure thresholds to different types of monitoring. For more information about the Global configuration and the options that you have there, please, reffer to the documentation in the link
Let me know if that helps,
The thresholds can also be set for individual URLs as well. That way, if you have a 3sec home page expectation and a 30sec report expectation, you can differentiate.
This is done from within the software service configuration. It would be at a more granular level than the global settings Avner described.