After creation of 2D drawings, the entire drawing act as a single entity including dimensions, levels, position flags etc and no any manual modification is allowed.
1. Go to Utilities > Named Groups. One new dialog box will open.
In CONNECT Edition Go to Modeling > Home > Groups or Drawing > Home > Groups and click on the right bottom button
In that you need to tick off the box in Selectable column. The drawing then be editable.
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Bentley LEARN Server