Hey, welcome to LibreCAD!
To modify dimensions, you can simply drag the grippers.
When you select an entity, not only dimensions, you can see these little blue and green grippers.
Click on the entity and drag it to move it to another place.
Clicking on one of the gripper and drag it to modify the entity in place.
Try this and you will see how it works.
To move a dimension with its related entity, select both and drag them or use the Modify - Move/Copy tool.
Armin
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