Hi @CreativeCoder and @CeeCee, I tested out editing a poll and, like you said CeeCee, it says you can't add or remove poll options after 5 mins. You can change the names of the options though it seems.
The computer recommends closing the old poll and making a new one if you'd like to add or remove options. I think it does that so the results of the old poll are still kept.
And totally fine question Creative Coder I used an app called Paper to annotate that photo. It's free to download and it's easy to use, and it's a great app for drawing but you can also use it to draw on pictures.
And @Stradyvarious, like @CreativeCoder said, you can choose whether or not you want your poll to have multiple choice or just single option. You can check the link I referred to at the very first post on this topic for more info too (that link is here)