SW 2014 x64 SP3.0

I have scanned lots, and I mean lots, of forum posts and google results and keep coming across the advice to "open the routeAssembly.asmdot template and change the settings as required" but I have yet to see any instruction on how to do it. The file is not recognised when I double-click it in Windows Explorer and Solidworks does not recognise it through File / Open.

We are creating successful routes in our assemblies using the default standard imperial tubing, but are experiencing a few issues that we think can be solved by editing the template: tubing colour; tubing material; metric dimensions. We only use four different sizes of airline tube and they are all the same material and colour.

Any simple instructions on opening template files would be appreciated, thanks. (We think we are OK with file locations and part configurations, though by no means proficient !)