Teams not using my account to join meetings, making me join as guest

Thanks for your reply ChristianJBergstrom, I recently removed 2 organisation from the Teams app so now it just has my personal account. I was having trouble removing one organisation from the list in the Teams app despite leaving the organisation through steps I found here, so spoke to tech support to get that resolved thinking that was blocking my access, as I haven't been able to switch between accounts. I only have my personal account listed in Teams now, but sadly the problem still exists. In the process of getting the organisation removed, the cache was cleared so there is nothing there now. I am the only one who uses this account and computer as it's for work. I don't have outlook linked to my Teams account and neither does my colleague so don't think that is the issue. The only difference between my colleague and myself is that I use gmail email address, he uses his apple email address, and I have an office 365 account but he doesn't, he has has also had one of the same organisations linked to his teams account, yet was still able to switch between accounts. Other than that, everything else is the same. I've also tried it on other devices with no luck. Any other ideas would be greatly appreciated. Do I need to see if I can contact Microsoft? When I spoke to the guy last week he suggested reaching out the community, which is why I posted here.

Update....I have been able to join using my personal account on my iPad using the mobile app, but not on my laptop or iMac desktop computer....Is it something to do with the the desktop app?  I wasn't even able to join on another device like I could when using organisation log in...but sadly iPad is too small to be able to work off.