@thewillrussell Then the samples you are using are wrong.
As for romsets, make sure the samples you are using are meant for the arcade emulator you are using.

@mitu
Oh. That's rather disappointing. I suppose I will have to stay on the lookout for an emulator of xbox that supports arm64.

@psun03 In addition to what @sleve_mcdichael said, you can see the name and location of the remap file in the log:

... [INFO] [Remaps]: remap directory: /opt/retropie/configs/arcade/ [INFO] [Remaps]: game-specific remap found at /opt/retropie/configs/arcade/MAME 2016/tokyowar.rmp. ...

@mitu Using the standalone version of MAME, most recent version. And if you run merlin, mmerlin, mbdtower, starwbc you can see this happen.

Read the installation instructions for the MAME version you want to install - if you don't find it in the the software center, then you'll probably have to compile it or download a pre-compiled version.
Once you get it installed and running, then you can probably modify the Emulationstation configuration to add a new system for this new MAME version - something similar to https://retropie.org.uk/docs/Add-a-New-System-in-EmulationStation/.