Downgrading to an older version
There are various reasons why you would want to use an older version. For example your computer is too weak to run the more advanced versions or you are using old mods.
Older versions can be found on the changelog history page. Each version is linked by their green high-lighted version number.
If you want to run it along side other versions simply install it in a different folder. After installation create a short cut if necessary and with the appropriate name.
Different versions may have different settings. In this case you could add a
--rootsavepath C:\Cosmoteer_0.13.9_Saves\ to the shortcut to keep the settings and saved ships/games separate.
Savegame and ship files
Most of the time these are safe. However, several times in the past changes have made them incompatible or moved their location. Please check the changelog.