The Replace Block dialog box appears when you select a block and click Replace on the shortcut menu in either the Block Library or on the drawing sheet.

Select Block

Specify the name of the block that will replace the currently selected block, or click Browse to find a document that contains the replacement block.

Apply Changes to All Occurrences of This Block in the Active Document

When replacing from the drawing sheet, you can set this option for a global replacement of all instances of the selected block in the active drawing sheet. Clear this option for a single block replacement.