Audacity Audio Changing

[jay123210599]

How do I use use Audacity to slowed and reverb audio, as well as increase the volume of audio files?

[GeoffreyA]

After opening the file, click the big box on the left to select all the audio (alternatively, press Ctrl + A). From the Effect menu, select the modification you'd like to apply, such as "Reverb." For increasing the volume, try "Loudness Normalisation," using a smaller number: for example, -16 LUFS. To slow down the audio, I'm not sure what is the standard way of doing it, but there is a "Paulstretch" filter that seems to work.