Hi,

1/ That's sticky sidebar - it's sticky when you scroll down or scroll up. If you don't want to use sticky sidebar, you can disable it via Customize > General > General Settings > and un-check on "Enable Sticky Sidebar"

2/ To display recent posts in 2 columns - please go to Appearance > Widgets > drag & drop widget "Soledad Recent Posts" to "Main Sidebar" and check to "Display on 2 columns"

3/ If you display it in 5 columns, it's very small and maybe you can't see anything. And we don't support to display it in 5 columns.

Best Regards,

PenciDesign