I have Visual Studio 2017 installed alongside Intel Parallel Studio XE 2018, and have tried to use these instructions to select an older version of the compiler to use. However, I cannot find older versions of the compiler (17 and below) under Tools > Options. I also can't find any reference to older versions in the directory C:\Program Files (x86)\IntelSWTools (is this the correct place to be looking?). Any help would be very grateful!
You need to have previously installed the older version(s), and the version you want must support the VS version you are using.
Ah, I think I was mis-interpreting the line "With the 2018 version, you have access to compiler version 14.0, 15.0, 16.0, 17.0 and 18.0" as meaning that Intel Parallel Studio XE 2018 comes with 14-18, rather than it works with previously-installed versions 14-18.
I presume older versions aren't available to install separately with a 2018 license?
Yup you can download and use older versions that are at at the intel download centre but you need to be mindful of what versions of visual studio a fortran version is capable of integrating with.
Every compiler installer that I have obtained from Intel contains exactly one major-minor number combination, e.g., 2017-Update4. You can look up the corresponding release notes to see which hardware-OS-VS combination is suitable for that particular installer.