LiteSpeed will not allow number of threads in both backup wizard advanced options and LiteSpeed Defaults to reach the maximum value supported by the engine for the appropriate SQL Sever version.
The number of threads came up as Default (n-1). The greatest of threads in LiteSpeed is 32. Numbers greater than 32 can't be entered into the LiteSpeed GUI. However the higher number can be entered when using scripts.
Development has a ticket opened to address this.