Enter a valid and then empty master password to remove encryption from previously protected password records. Close WinRAR and open it again after specifying the master password if you wish to see how protection works.
Once entered, the master password is valid until WinRAR is closed. If entered password does not match the master password, it is treated as a usual password for archive operations. If saved passwords are protected with master password, you need to enter the master password and press 'OK' in password prompt to access them. Use 'Set master password' button in 'Organize passwords' dialog to encrypt saved password records and protect them from unauthorized access. If you already saved RAR format in the default compression profile in previous versions, WinRAR respects stored settings This change affects only new clean installs.
If you prefer RAR 4.x format by default, use 'Create default.' button on 'Compression' page of WinRAR settings and set 'RAR4' in the displayed dialog. You can change it to RAR 4.x compatible format with 'RAR4' option in archiving dialog or -ma4 command line switch. WinRAR and command line RAR use RAR 5.0 archive format by default.