Need small adjustment for download radius of tiles

Sounds a silly question but i have been playing arround with the Lod and mapping but dont fancy messing it all up again just got it nice now,can someone just confirm this, i would like to increese the radius in wich it downloads tiles around my aircraft , reason behind this i can just leave my pc over night and it will download lots hopfuly, but at the moment you got to fly about like a fly ,any Tips or adjustments i can make ? many thanks