You can upgrade the IDE and continue to use an older toolchain if required. For example, you can have a QNX Software Development Platform version 6.5.0 installed on the same machine as QNX Momentics 6.4.1, 6.3.x and 6.2.x, and in most cases, the IDE installed with version 6.5.0 should work with the toolchains from these earlier releases.
To upgrade the IDE and use an older toolchain, do the following:
Once you specify the Use Environment Variables option, when you start the IDE, it uses your current qconfig choice as the default version of the OS; if you haven't chosen a version, the IDE chooses an entry from the directory identified by QNX_CONFIGURATION (the location of the qconfig configuration files.) If you want to override the IDE's choice, you can choose the appropriate build target.