I seem to have accidentally converted my drive format to APFS. A few years ago I installed a WD Black2 Dual drive. This all worked great. Recently, I began to notice that the boot took a long time and would stop at about 75% complete, eventually finishing and booting normally. After a bit of poking around I noticed that the format of the partitions were now in APFS format. The OS seems to recognise the drive as an SSD and has converted it to APFS. I'm not sure what to do now. Any advice?