Definitive solution for ir remote repeat issues

I have setup 2 pi/3 boxes with Libreelec. I wired my own remote IR receiver and added the statements necessary to the config.txt to enable the ir remote.

The remote works but when I hit <down> once it repeats numerous times. When I hit any button, it seems to repeat numerous times. I've added

<advancedsettings>
<remoterepeat> 2500 </remoterepeat>
</advancedsettings>

to the advancedsettings.xml file and it made no difference. Someone suggested adding lines to the peripherals.xml but nobody explained how to make this file writeable.

Can someone help here?

Thanks!s

Seems to have settled down a bit. This is my advancedsettings.xml:
---------advancedsettings.xml--------------
<advancedsettings>
<remotedelay>3</remotedelay>
<remoterepeat>2501</remoterepeat>
</advancedsettings>