Elevations

[robblight]

When creating a template how does one change the elevations so by default it starts at 100'-0" instead of 0'-0"?

[Revitaoist]

Elevations have a parameter called 'elevation base' in the properties. They can be set to "shared" or "project". If set to project, first floor will always read 0'-0", if set to shared, first floor will be whatever the real position is. Set it to shared and move the levels vertically 100'. Now change them back to "project" to get first floor reading 0'-0". Now when you do an elevation callout you will have similar options for what elevation is shown, project, or shared.

[Dimitri Harvalias]

I will caution you that this can cause issues when collaborating with others. Make sure everyone is aware that you have modified the project location.
Keep in mind this can also be problematic when you want to add spot elevation markers, to toposurfaces or similar, where you want to indicate actual geodetic elevations. Everything will be off by the 100' you have moved the project.