Okay, I've had this problem for like 2 years and I'm absolutely pissed off about it. For some reason, (even though I have set "Delete History" to "Manual") my Safari history keeps getting deleted. For example, my oldest entry is 2015, 29 January. Yesterday when I checked it, the oldest date was 2015, 28 January. So for everyday that goes, it keeps deleting my history!
Why does this problem occur? And before you say that I should delete my history file; I already did, I tried that back in October but I still have the same problem.
defaults read ~/Library/Preferences/com.apple.Safari.plist HistoryAgeInDaysLimit
into a Terminal window and tell us the result.HistoryAgeInDaysLimit
. I would guess that setting it to 999999 would max it out. Datatype is integer, so it could be larger. Btw/ 999999 days is 2737.91 years.