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Hi,

You need to switch to Layout with drop down list on the Status Bar:

Than adjust paper size via Page Setup Manager (menu File -> Page Setup Manager -> "Gear" button -> Modify)

Than delete existing viewport in the Layout and create new Viewport with button on Layout Visor (top of the screen)

Select viewport you just created, and select "1:50" scale from drop down list on the Status bar.

Double click on viewports border, this will switch you to the Model space, adjust the position of the drawing with PAN command, don't use ZOOM command in order to preserve viewport scale.

Double click outside viewport to switch to Paper space (Layout).

Now create title block in the Layout.

Maxim