Mount options affect the parameters of the volume being mounted. The Mount Options dialog can be opened by clicking on the Mount Options button in the password entry dialog. When a correct password is cached, volumes are automatically mounted after you click Mount. If you need to change mount options for a volume being mounted using a cached password, hold down the Control (Ctrl) key while clicking Mount or a favorite volume in the Favorites menu, or select Mount with Options from the Volumes menu.
Default mount options can be configured in the main program preferences (Settings -> Preferences).
Mount volume as read-only
When checked, it will not be possible to write any data to the mounted volume.
All volumes created by VeraCrypt contain an embedded backup header (located at the end of the volume). If you check this option, VeraCrypt will attempt to mount the volume using the embedded backup header. Note that if the volume header is damaged, you do not have to use this option. Instead, you can repair the header by selecting Tools > Restore Volume Header.
Mount partition using system encryption without pre-boot authentication
Check this option, if you need to mount a partition that is within the key scope of system encryption without pre-boot authentication. For example, if you need to mount a partition located on the encrypted system drive of another operating system that is not running. This can be useful e.g. when you need to back up or repair an operating system encrypted by VeraCrypt (from within another operating system). Note that this option can be enabled also when using the ‘Auto-Mount Devices’ or ‘Auto-Mount All Device-Hosted Volumes’ functions.