I upgraded to HeidiSQL 126.96.36.19919 a couple of days ago, and have discovered an annoying issue that wasn't present in earlier versions.
I've set Grid Formatting:Font to Tahoma 8 pt, but every time I run a query, the font is reset to, at least, another size.
If I run a query, and then go to Preferences, and then switch the font size one up, then one down (to make the apply button active), I can apply, and the font is set to the right size.
If I run the query again, HeidiSQL resets the size once more. It is "fixable" by zooming with crtl-mousewheel, but it is pretty annoying having to do this after every query.