I know there’s an option to decrease No. of columns, but I can’t find it. To be exact, I now have 2 columns on every page of my blog, but I want to display only 1 column (the one without widgets) on posts and remain 2 columns everywhere else (f. e. homepage).
Sorry, It is not possible to display one column in some page/posts and 2 column in others. You can either display one column or two column throughout the site.