Complex sentence: Follwing the intrest from record labels, the band and their manager, who had been using a variety of band names such as'Quartech', decided to change their name and sign their record contract as'N-Trance'.
Split into simpler sentences: Follwing the intrest from record labels, the band and their manager decided a new band name was needed. Previously, they had been using a variety of band names such as'Quartech', but settled on changing their name and signing their record contract as'N-Trance'.