No problem. So you are using the default internet browser either by using the internet icon and going to google.com or using the google search widget. Got that understood now.
I couldn't figure out where you were getting this "options" selection. But I finally found it. You are using the browser in "mobile mode". In desktop mode you do not get the "options" and that is what I use. I enlarged the screen as you say you have done. I select "options" and it brings up the 3 choices. I try to select "cached". It seems sometimes it shows a bigger green square selection (not just around "cached") window and makes it look like I am not selecting "cached" but it actually brings up the cached page for me.
Try this and see if it helps. Select "options" and then after the 3 options appear, resize the screen just a small amount and see if you can select "cached" clearly. Seems to work for me. Most likely a bug in the browser.
I would suggest you use desktop mode but since you do like the "cached" option you better stick with mobile mode.
This may have something to do with your issue when responding in the forum. So I tried responding in the forum using mobile mode and didn't have the issue either. After tapping in the text window, the keyboard pops up. I am able to scroll around and place the text box where I want it. So I can see most of the text box. Then as I type the window will actually move with the text.