Increase volume on multiple files at the same time

Is there a way in Audacity to select multiple files and apply the same increase in volume to all of them? I don’t want to normalise.

You can batch process with a “macro” (see: and use the “Amplify” effect in the macro.
Note that when used as a macro command, the Amplify effect has no protection against clipping - if you amplify too much, it will cause (permanent and irreparable) distortion.

Thanks very much for the quick response.