How to fix "signatures do not match previously installed version" error?

I'm using a Moto G6. With the latest update to android 9, they removed the capability of using the built-in Dolby Audio equalizer for some stupid reason. I found this Reddit post that had a way to modify the APK to make this work. I followed all the steps. I decided to try the 20 band equalizer steps and made a backup of the previous work before starting. However, when I finally got to the ADB install DaxUI2.apk, it didn't work. I got this error: >adb: failed to install DaxUI2.apk: Failure [INSTALL_FAILED_UPDATE_INCOMPATIBLE: Package com.dolby.dax2appUI signatures do not match previously installed version; ignoring!] This was saddening, but no biggie, right? Because I already had a backup. I renamed the DaxUI2 folder to DaxUI2broken, renamed my backup to DaxUI2, and I tried again, with just the first part (minus the appendix). Once I did this, though, I got the exact same error. I'd like to be able to fix this, so if anyone knows how, please tell me!