Drop down version menu does not appear in launcher

I was in 1.15.1, and wanted to switch back to 1.15 in order to get onto a server that was still in 1.15. I did not have 1.15 as an instillation, so I found the "new" button. I named it, set the block icon, but no matter where I clicked or what button I pressed I could not see the version drop down menu, and cannot get back on to 1.15