This all depends on how the Carriage and Installation amounts are inserted into the project.
Using Details Panel
Inserting a Carriage amount in the "NET" column of the details panel will prorate per item depending on the weight. The prorated amounts will show in the "Net Carriage" column of spreadsheet and it can also be broken down per item on the Quote report.
Inserting the Carriage amount in the "SELL" column in the details panel will not prorate per item and just show as a total at the bottom of the Quote report. This also applies when using the “Installation” amounts in the same way depending on what column you use in the details panel.
The report option to show Carriage or Installation on Quote report per item (if entered correctly) is called “Show in Item Total” as illustrated on the snapshot below.