Is it possible to change the grid size in Quartus II schematic window?
From the Help:

Quartus II Help v15.0 > Creating Designs > Using the Block Editor > Viewing Blocks and Symbols

On the Tools menu, click Options.

In the Category list, select Block/Symbol Editor.

In the Guideline spacing box, type or select the default guideline spacing for all new files.

To snap to the grid, turn on Snap to grid.

Click OK.

It worked OK when I tried it.