Complex sentence: However, on 21 February 2015 it was announced that the host city had been changed and the contest would then take place in Ashgabat., however, in late August 2015, the host city was changed yet again to Istanbul, Turkey.
Split into simpler sentences: However, on 21 February 2015 it was announced that the host city had been changed and the contest would then take place in Ashgabat. In late August 2015, the host city was changed yet again to Istanbul, Turkey.