I'm glad to help Since no one is giving full on information... I will do my way and HELP real reople like you.
Yes always 1 single word name. CREEPIESTTALES sounds ok. However one small issue. There are 2 T T letters... Dont let that fool you... CREEPIEST TALES to be merched together is correct but the faults is that 2x with T beside might confused other people. BUT not always... Maybe: CREEPIESTSTORYS or CREEOIESTTHINGS But i do like the nickname your chosen. Just the odd having 2x T beside might confused people because what happens is...people might think to spell your channel is it (CREEPIESTALES or CREEPIESTALES) See the diferences ? usually having double same letter might be a bit confusing. However maybe just leave it as it is like you have. If you wish to re-edit the name you can within 14 days or every 14 days time. As long the name is not taken. And the rest sounds good. The reason why i say keep it high capitals letters is just so it stands out to the rest of the youtubers out there.. BIG to see the name rather then low capitals.. I have mine big capitals and i have the name no longer then 8 letters together. The shorter the easier for people to find your channel. The longer the name is the harder it can get or people might forget the full name to the channel. Uusally people will always remember a short nickname to it. Yours now sounds good... Oh though... the double T letter that is together in your current nickname you create is might be slightly confusing for some people. Just thought ill point that out just incase.
I would never use nicknames like lets say for example KENNJACK.. because what happens is... is people might say is it to be found as KENJACK OR KENNJACK... and why i say this? Because having 2x same letter beside N N is confusing just like yours with T T beside them. It if had 1x then it should be good. But then again your channel name has to make sense and spelled correctly otherwise.. You sure wouldnt want to have it as CREEPIESTALES.. because something is missing how its spelled but same time easy for people how to find your channel. But same time misspelled. So if i was you maybe change it to soemthing else CREEPIEST______ With something of your choise but making sure you dont end up having a far too long nickname. Long nicknames end up been too dificult for many. Shorter nickname will be easy to recall and remember for others.. But i guess the nickname your choisen is OK. nothing wrong with it. Only issue is that double TT together..... people might think your channel name is CREEPIESTALES. But you have it CREEPIESTTALES which is the correct way of spelling it but also making it confusing for people if its just 1 t or 2 T's to it. Mmmmm but i like the name your choisen in my opinion though.
Anyways you do not need to change it if you dont wish to. Just the double t's together might be a worry. Thought i let you know that. The nickname sounds cool. I actually like it. But yeah just the double T's beside it might be a slight concern only.
I usually use (Nickname youtube generator) just type that on google search and you find heaps of websites each them out play with it. It will slightly help you make one like CREEPIESTTALE into something similar name under 1 single name.
Remember dont go into sepoarated names to the channel. Like is said above.. Dont make the nickname to sound like CREEPIEST TALES. But rather 1 single name CREEPIESTTALES... 1 single name like that is so much easy for people and really easy to remember. Like i said... you cant always remember peoples full names out there everytime because you might forget how to or spell it. If every human person only had 1 single name then it would be easy to remember everyone rather then Jack ken smith or Jack ken lopster but rather more (jack) and nothing else.
For thumnail i always use :VistaCreate" Website.. i use it every week for title to my videos covers... like if your video is about a scary house story. I will label a picture with the name over it My scary house part 1) or something like that. VistaCreate are free so i always use it for youtube.
Yeah i feel you. I dont work. I have youtube to keep my life active and feel great... if only i hope to be fame and rich oneday im still waiting for that 1,000 subscribers to start with. I only have 510 subscribers. Slow.. But thats how life goes.
All the best.