Until you get a capo, you can use a short strip of blue painter's tape to hold the loop in place while you change a string. Probably best not to remove ALL the strings at once. Pull one, replace one... and repeat. If the bridge is not in a slot on top the fretboard, and you remove all the strings, getting the bridge back in the correct place to the nearest millimeter can be a major problem.
I'm really glad I saw your post, Ken. I always used to remove all the strings on my guitar when I changed them out because it also gave me the opportunity to give the fretboard a good cleaning more easily. I have to remember this when I get ready to replace my dulcimer strings!