There can be a number if things that cause poor cut quality.
1. The speed on the cutter may be too high, you can try lowering it a little bit. ( you cannot go to slow and for small or detailed cuts you will get the best results with a lower cutting speed.
2. The material may be shifting during cuts slightly. You can try cleaning the rubber wheels with a damp cloth to remove any dust or dirt which can cause the wheels to loose grip on the material. Also make sure the pinch roller wheels are in the correct locations with the grit roller bar directly below each one and they are spread evenly across your material.
3. the X or Y belt may be loose on the cutter or the carriage wheels for the cutter head may not bee seated on the rial properly. Make sure there is not excessive slack in the belts and the carriage cutting head is properly seated on the rail of the cutter.
4. In SignCut there is a setting that controls the detail of the corners called "blade offset" You find the blade offset in Pro 2 by clicking on the scissors, then click on the the tools setting tab. Here is a video that shows what this setting controls and how to adjust it. https://www.youtube.com/watch?v=Wfibwv02PSQ
Usually a blade offset of about 0.03cm, 0.3mm, or 0.0118 inches is sufficient but sometimes it needs to be set slightly higher. It is best to cut a T then look at the corners after it has been cut. If the corners are rounded, increase the offset slightly and try cutting again. If there is an edge protruding from each corner that means the offset is too high and needs to be lowered.
The last thing could be that you are trying to cut a detailed image or the text is smaller than the cutter can successfully cut. If larger text is cutting well then that is likely the case. There is a limit to the size and detail a cutter can successfully cut. Cutters equipped with servo motors are able to cut smaller text and more detailed images compared to the standard stepper motors which are equipped on most value model cutters.