If you would like to change scale of your drawing, open your drawing, then go to Environment > Drawing Page, choose the Scale tab and type in the Scale, eg. 1″=8’. After you have to change the scale, you will need to modify the text, leadered text and the arrow heads of the leader so that they are legible.
For text settings go to Entity > Text and change the height and width
For text with a leader go Entity > Dimension > Text and change the height and width
For dimension/labeling arrows go to Entity > Dimension > Arrows and change the Length, Ratio and Diameter
The settings are dependent on the scale, to verify what the default settings for the scale is, open a blank drawing of the scale you are changing to and write down the default settings then input those into the above.
Alternatively, you can copy and paste into a new drawing of the scale you would like to use, that way all the settings for the text and text with a leader will be the size set for that scale. Here are some instructions to assist with copying and pasting to a new drawing: Copy and Paste to a New Drawing