Sorry i didn't reply earlier. Yes, i'm still having problems and if you have any settings or options i can use then please, let me know! Thanks.
For me, when I tried to manually increase or decrease (desktop) Firefox's zoom level here at Era with ZPWE enabled, it would not save the setting and always reset to 100% each time I loaded a new page at the site. So leave that alone.
Changing the font size within Era's setting does nothing, so don't expect much from that either.
Focus on ZPWE's options and it should work out in the end. First, note that there are two option menus in the add-on, not just one. The first is accessed by clicking on the add-on's icon in the toolbar at the top of the browser. Eight squares in two rows of four each comes up, and here's what I have...
<Top Row>: Reset...Auto...Text...Reset
You only need to make sure the second and third setting match what I have. If you choose "Full" instead of "Text" in the third box, your Era forum pages will become very skinny.
<Bottom Row>: 28px...-...63%...+
The first setting there is a max 28px because it only affects a few header titles like in the UI around the forum which will be VERY tiny unless this number is used to make it look close to normal. The plus and minus buttons affect the percentage in the third square. This is why you need the second option menu that I will discuss in a bit.
By default, if you select 30% it is the minimum, and clicking "+" will increase it by the determined amount in the order listed when you click the third box: 30, 50, 67, 80, 90 ,100, etc. But what if you want 40 or 63 or 77? To get other percentages, use the second option settings by going to: Firefox's Option Menu-->Add-Ons-->ZPWE Options.
Once this menu is up, select "Zoom Levels and Font Sizes", then go down to the Zoom In/Out section. Change it from "to the next level" to "by fixed step 10%". You don't have to use 10%... use any number you like. For me, setting it at 10% allows me to go back to the first menu, and if I want, say, 63% size I can select 133% from the bottom row and then click the "-" button seven times to make it come down to 63%. If I want 57%, I can select the 67% size and click the "-" button once to get it.
Hopefully this makes sense.