Default Location
open your wallet -> help -> debug window -> datadir
check what it says there
Windows
Go to Start -> Run (or press WinKey+R) and run this:
%APPDATA%\BitcoinC
BitcoinC's data folder will open. For most users, this is the following locations:
C:\Users\YourUserName\Appdata\Roaming\BitcoinC
"AppData" and "Application data" are hidden by default.
You can also store BC data files in any other drive or folder.
If you have already downloaded the data then you will have to move the data to the new folder. If you want to store them in D:\BitcoinCData then click on "Properties" of a shortcut to bitcoinc-qt.exe and add -datadir=D:\BitcoinCData at the end as an example:
"C:\Program Files\BitcoinC\bitcoinc-qt.exe" -datadir=d:\BitcoinCData
Start BitcoinC, now you will see all the files are created in the new data directory.
Linux
By default BitcoinC will put its data here:
~/.bitcoinc/
(or just copy and paste my commands below)
cd ~/.bitcoinc/
You need to do a "ls -a" to see directories that start with a dot.
If that's not it, you can do a search like this:
find / -name wallet.dat -print 2>/dev/null
Mac
By default BitcoinC will put its data here:
~/Library/Application Support/BitcoinC/
Oper finder ==> Press combine: Shift +Command+G==> input ~/Library/Application Support/BitcoinC
P/s: some Mac system will hidden file and need to config tho show it
follow this guide
https://ianlunn.co.uk/articles/quickly-showhide-hidden-files-mac-os-x-mavericks/