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Hi Carla,
>>>>I've attempted changing the scale
Where have you tried to change the scale?
What value does MSLTSCALE variable have?
If it is 1, then what about annotation scale? You can verify and change annotation scale on Status bar:
When MSLTSCALE=1 (the default value), it overrides global linetype scale factor (LTSCALE) and current object linetype scaling factor (CELTSCALE) according to annotation scale (CANNOSCALE)
Read more about linetype scale >>>here<<<.