How do I fix the upside down image - Fieldvision 114mm Reflector (114 x 114mm) Telescope

Astronomical telescopes usually show an upside down image. There is a good reason for this- erecting the image needs more bits of glass in the light path, which reduces the amount of light and increases aberrations. Even if this is only slight, astronomers prefer to avoid it, and they don't really care which way up the Moon or Jupiter appear.

It is possible to fit an erecting prism or eyepiece to most astronomical telescopes, and some of them come with one, but if you want a telescope primarily for terrestrial use, you are much better off buying what is called a "spotting scope".

If the telescope has a standard 1.25 inch diameter eyepiece, then an erecting eyepiece may be found on Amazon or eBay. An erecting prism or diagonal of the type that bends the light through 90 degrees is not right for a reflecting scope. These are used on refractors.