When I want to add images to my forum signature, i grab my IPad/tablet and search for something specific on Google. Once i find an image, I screenshot it. After screenshotting, I go to my photo app and 'copy' the image. After that, I log into HoFa on my IPad and paste the image there. Note that this only works with mobile devices and not computers!! :)

As of late, for me at least, imgur doesn't always work out but when looking at the text box ((I am on mobile so it will look differently than on pc or some other device)), up above the text box you will see Icons, like B for Bold, I for Italics etc. Scroll or look for the one icon that looks like this: <> ((It's in between Tx with a small line under it and the emoji icon)). Using this, in my experience, allows images to be saved from links/urls as its a source code. So you'd essentially still do the <img scr= option but put it all in that <> icon and save it that way.

Note also using source code on mobile helps with copying/pasting text around too.

I send myself the images I want fo use on Discord, and copy the link from there. For some reason, as Dusty said, imgur doesn't always work. 

Update: the copy and paste method worked! Thanks ya'll :D