How to set grid layout and 3 columns in Thumbnails block

Hi there!

I've got question about Thumbnails block in composer.

After selecting photos from my hard drive and after loading it to my blog post, by default thumbnails view is set to 'Stack' view and divided to 4 columns.

My question is - where can I set default option for it, to 'Grid' view and 3 columns?

I'll set it to default option for every thumbnails block.

Where can I set this?

I'll be vergy grateful for your help!
Best regards!
Adam