If you would like some advice about how to get your mixes to sound equally loud, I would look into finding a loudness meter plugin. These plugins typically have a measurement called LUFS, which measures the relative loudness of the entire track. I don't think FL Studio has a loudness plugin built in, but I looked online and it seems there is a free one.
Video link for more information: https://www.youtube.com/watch?v=ANzd6xQDJRM