I set up a chain. I goto File > Chains > Edit Chains > this is where I select ADD and name the thing. Then INSERT, then choose CHANGE SPEED then slide the percent slider to -16% like I want.
Great, or so I thought.
Now rather than sit and wait hours and find my computer has done the wrong thing as life has taught me I try it out on one file one.
I goto File >Chains > Apply Chain > Select the one I made above > Apply to Files, select the file im demoing it on…
On hitting open the file is automatically opened in Audacity and screens indicate the process is being applied all how I would expect it to be.
However when playing the initial file back, there is no change at all.
I am left wondering is Audacity saving this file to a new location and not changing the original. I cant see any options on the Chains Edit menu to specify this if so.
Seems like you have worked it all out, but to fill in a few details for other readers:
Audacity does not act directly on audio “files”. When working with files, Audacity acts on a copy of the audio data that is “imported” from the file.
Similarly, to save the audio data from an Audacity project as an audio file, it is necessary to “export” the data to an audio file.
“Saving” an Audacity project saves the current state of the Audacity project, which may contain multiple tracks, multiple audio clips, labels, envelopes, an other data. The “Undo History” is not saved. Saved Audacity projects have a “project file” that end with “.aup”, and a data folder that ends with “_data”. The “_data” folder contains the audio data and the “project file” tells Audacity what to do with that data. More info about Audacity projects here: https://manual.audacityteam.org/man/audacity_projects.html