Microstation relies on the seed file being a 3d seed file. GuideSIGN Markings provides a suitable Keysoft.dgn file with the appropriate settings within it. This file can be copied and renamed if you want to modify the seed file for other purposes but still use it for GuideSIGN Markings. Using the desktop icon to start Microstation and GuideSIGN Markings should allow you to pick this default file.
There is a default template drawing provided with GuideSIGN Markings is called Stripe.dwt. If GuideSIGN Markings is set up in the recommended way, every new drawing started from the GuideSIGN Markings desktop icon, will use this template. It is possible to change this template file by opening and editing it, but as described in Template Settings, it is also possible to specify another template file as an alternative to the default one.
GuideSIGN Markings should no longer require a specific template to be used, so any template that the drawing office requires should be fine to use. However if you want to make the desktop icon start with a different template dwt, you should also change the ‘Target’ item of the desktop shortcut. Right-click on the shortcut icon and pick properties, then look at the target line and find an item /t. The file after the /t inside “” is the default template used by the desktop icon, and this can be changed to any other file name.