Since it's been about half a year since I last updated the 64-bit version of QB64, I went through the process to get the QB64x64 version up to date for us so everyone can take advantage of the newest commands, bug fixes, and alterations to the language.
Compressed size is about 90 MB, and the file is in a standard 7z format. Download, extract where you want it (a new folder please, not over an old one, unless you just like issues), and you're good to go.
NOTE: Newest version of the c-compiler which is packaged with this version of QB64 has now updated to the latest mingw version 8.10. The old compiler we were using was from back in 2014, so look for any changes/inconsistencies in how it behaves and feel free to report them to me. I think I've ironed out all the glitches, but until people stress test things fully, I won't swear it's all 100%... I *think* it is, but...