Welcome to TSP Eaw, enjoy your time with us - we are a very friendly forum and always willing and able to help others.
I see you have a Bernina 830 Record - lovely machine - in fact I gather this is the machine that Bernina got totally right back in its day and is a total workhorse and so reliable. I have inherited my mother's Bernina 830 and use this as my day to day machine - perfect stitching and a joy to use. (I do have other machines) I particularly like the corded buttonholes - and the instructions for these in your instruction booklet are so easy to follow and give such a neat buttonhole. In fact I have used this method of doing buttonholes ever since I first tried it out on the 830, and I use perle embroidery thread No5 which I find is a great thickness and this is the one that comes in a skein. I also close the stitch length up and find this totally covers the white cord, so I do not have to go buying matching perle thread to match each garment - if you have never tried this, do give it a go and I think you will be surprised at how easy it is to sew and also what a lovely buttonhole it gives.
Enjoy your time with us and we look forward to hearing and seeing what you are making.