There are two kinds of TEMP environment variables in Windows: user-level and system-level. The former is used by regular applications you launch. The latter is used by the system and services.
When you change the TMP/TEMP variables from the RAM Disk app, it only modifies the user-level variables. This is done for safety, because the system-level temporary folders are crucial for normal operation. If system-level variables point to a RAM disk and for some reason the disk is not available, the system may fail or refuse to boot.
It is possible to override this manually and redirect the system-level TMP/TEMP to a RAM disk, but there is a risk of breaking the system. In most cases it should work fine though. If you want to try it out or inspect the variables, press
Win + R (Run), type
sysdm.cpl, then go to
Advanced - Environment Variables: