AI and SVG generally use real units, so if you have AI or SVG files importing with an incorrect scale, email them to us at support@lightburnsoftware and we’ll have a look.
DXF is another matter - the files generally don’t contain the unit of measure they were created in, and sometimes when they do it’s wrong. You can set ‘auto-detect’ and that works most of the time, but if it doesn’t, you can turn that off and manually choose the unit for the file before importing (as Ralph shows above), and that should work.
Saying “they all import with wrong scaling” is not specific enough for us to try to help you. If you said instead, “they all come in about 3/4 the size they’re supposed to” or, “AI files are 2x too big, SVGs are 50% too small, and DXFs have no consistent pattern”, that would be better. If you can be as specific as possible, we can help you faster.