Audution CS 5.5 インストール

Audition CS5.5. is now a very old version.  I suspect your new computer's monitor's resolution is UHD (Ultra High Definition).  As a result, the icons for any programs that are not High DPI-aware will not adjust their size to make those icons anything other than very small.  I'm certain AA CS5.5 is too old to be High DPI-aware.