I went to change my spells and was able to unprepare some, but now every spell I click on only expands the description in the sidebar as well as the character editor. I use chrome, but it is also happening with edge.

Click the prepare button to the right of spell name. If it is grey, then you reached your preparation cap.

I have an available spell slot. I wanted to swap out spells after a rest, I unprepared one spell and I am unable to prepare any new spells. 

Link the character.

Playing again this week, still doing the same thing. However I have found clicking the prepare button to expand the spell then clicking the prepare button at the bottom of the spell does let me prepare it. It also lets me prepare as many spells as I want over my limit.

https://ddb.ac/characters/5487338/c7cdoh

Dont use the share link. Link the character sheet URL.

I also had this problem (and found the same solution, using the prepare button inside the spell description), but that doesn't work for sorcerer in my party, who needs to Learn spells.

Quote from nicktresco >>

I also had this problem (and found the same solution, using the prepare button inside the spell description), but that doesn't work for sorcerer in my party, who needs to Learn spells.

 I'll tell you what I told the other guy over a year ago: "post a link to the character"

Quote from DxJxC >>

 I'll tell you what I told the other guy over a year ago: "post a link to the character"

I don't know how to do that. If I simply post the character sheet URL you won't be able to view it.

Anyone can view a character sheet that isn't set to private. But this is mainly to help the mods diagnose what might be wrong.

Also, please don't necro old threads.

Ah, I see. Here is the sheet:

https://www.dndbeyond.com/profile/nicktresco/characters/26652099

I have an open 4th level slot but the 'prepare' buttons are greyed out.

Spell slots are the number of spells you can cast, not the number of spells you prepare.  Clerics prepare a number of spells equal to their wisdom modifier+Cleric Level.  So your character prepares 10 spells, not counting your domain spells which are always prepared.  You can use any combination of leveled spells you want, as long as they add put to 10.

Quote from ArwensDaughter >>

Spell slots are the number of spells you can cast, not the number of spells you prepare.  Clerics prepare a number of spells equal to their wisdom modifier+Cleric Level.  So your character prepares 10 spells, not counting your domain spells which are always prepared.  You can use any combination of leveled spells you want, as long as they add put to 10.

Thanks! You're right, that's it. I thought I knew what I was doing, but I never played a "prepared spells" caster before, just bards etc.

imo the PHB would be improved by including, in Chapter 10 , a breakdown of how different casters work. I'm pretty sure that Wizards, Clerics and Druids work the same way, as do Bards, Sorcerers and Warlocks. Maybe they have some minor differences, which could be noted, and obviously there are other casters too. But seriously.

Anyway, thank you, also sorry for the necro. I though it sounded like the same issue, but I guess it probably wasn't. I suspect I can help my party's Sorcerer sort out her similar issue by inspecting the rules a little closer.

Wizards work very differently than clerics or druids. Druids and clerics are very similar. Bards and sorcerers have similarities. Warlocks are their own thing, very different from the other casters.