Did ACX complain about it, or are you guessing?
I probably wouldn’t use the phrase “Normalizing” because Effect > Normalize is an included tool with basic Audacity and it’s way too simple to correct volume problems such as yours.
As you noticed, the mastering tools all assume you were reasonably good at staying at one volume as you perform. This isn’t accidental. Fixing volume variations isn’t particularly difficult, but maintaining ACX Conformance while you do it is almost impossible.
Most home recording has high background noise and just squeaks by ACX Check. Correcting volume variations will cause the noise to “pump” and change over time. So even if you do manage to pass a straight noise test, you will probably fail Human Quality Control later for Excessive Processing. ACX doesn’t like you beating your voice with a stick before you submit.
We publish LevelSpeech2 as a plugin.
https://forum.audacityteam.org/t/improved-leveling-for-speech/33258/27
And you can try the older Chris’s Compressor.
Chris intentionally designed this compressor to correct operas so he could listen in the car without constantly turning the volume up and down. I use it so I can listen to spoken word podcasts while hiking—again, without constantly turning the volume up and down.
https://theaudacitytopodcast.com/chriss-dynamic-compressor-plugin-for-audacity/
Any idea why your volume is changing? Are you being too theatrical? Experienced users know how to back away from the microphone when they have to yell and get closer when they whisper. The theatrical affect comes through without changing the volume.
Even if you’re not constantly watching the Audacity volume meters as you should, you can go a long way toward self-correcting by wearing headphones and listening to yourself as you perform. If your microphone system doesn’t allow that, then it may not be the best system for you.
Koz