how do I set a default CALC new sheet size, ie: (15 columns x 50 rows)?
Hello,
you cannot do that - each sheet has 1024 columns and 1048576 rows (always). You could create a new (default) template which hides 1024-15=1009 columns and 1048576-50=1048526 rows.
See the following sample template file: Template-15x50.ots
Hope that helps.