Guangzhou and Quanzhou are two separate cities. Guangzhou is much more well-known than Quanzhou, so they probably thought you were talking about that instead. To be honest, I'd never even heard of Quanzhou until I googled it a second ago!

Now there isn't a city called 'guanzhou'.‘泉州(quán zhou)’ is a city in Fu'jian province, while '广州(guǎng zhou)' is the capital city of Guang'dong province. It may be difficult for a non-native-Chinese speaker to pronounce 'q'. And 'q' is pronounced like a 'ch'. If you can pronounce '去(qù)', then you know 'q' is very different from 'g'.

Maybe your Chinese friends confused 泉州 with 广州。However，广州 is spelt Guangzhou，not Guanzhou。

quanzhou = 泉州 guanzhou = 广州 copy-paste them to Translate Google and hear the difference * "q" is pronounced as "soft ch", while "hard ch" is "ch"