Adding audio filters to your clips can be a somewhat time-consuming affair, particularly if you have a known problem such as camera hiss. If you need to remove this problem from all the clips on Audio 1, you could either add the Lowpass filter to each clip, or you could copy and paste it once you have the right setting. Even with a custom-saved preset, this can be time-consuming, although you could select lots of clips and drag an effect onto them all. Alternatively, this task will show you a way to add any filter to all the clips on any audio track using the Audio Mixer.
Globally add audio filters to audio tracks by following these steps: