Can anyone help with anti-virus setup on how my drive is actually scaned?

there is a section in my antivirus software that allows you to choose how your drives are scaned but i dont understand what they mean or which is the best option or most thorough here is a list of what i have

Skip offline files: If the offline bit is set, the file is skipped. Any application may set the offline bit without actually placing the file offline.
Open files using backup semantics: This option allows the scanning of files that for security reasons are not normally readable except by a specific user.
Skip offline and sparse files (default): Some applications set the file sparse bit to indicate that part of the file is not present on the disk. Because some HSM products set this bit and other don't, consult your HSM vendor to verify whether the sparse bit is set.
Skip offline and sparse files with a reparse point: Some vendors use reparse points. An application that uses reparse points will also use an appropriate device driver to manage reparse
theres more didnt fit here

the rest of it...
Scan resident portions of offline and sparse files: identifies resident portions of a file. If the file is sparse, only the resident portion is scanned; the nonresident portion remains in secondary storage.
Scan all files, forcing demigration (fills drive): The entire file is scanned, which forces demigration from secondary storage if necessary. Because the size of the secondary storage is usually greater than the size of the local volume, this setting may fill the local volume and cause further files that are opened for scanning to fail.
Scan all files, without forcing demigration (slow): copies a file from secondary storage to the local hard drive as a temp file for scanning, but the HSM application leaves the original file on the secondary storage.
Scan all files recently touched without forcing demigration: lets you specify that only files that have been migrated recently and may still reside on faster secondary storage are scanned.

maybe when you tried to install the program, there was a virus on it already and the installation quit on you.