Usually you can easily change this in your 'config.lua' file. And if you have experience stages enabled you could take a look in your 'stages.xml' file.
if i want this exp from level 1-40000 level,50x 40001-80000 level,40x 80001-120000level,30x 120001-16000level,20x 160001-10000000 level,10xAs I said earlier: