I've had more than one bank for years and no problems whatsoever with Bangkok Bank. It's imo better than most other banks when it comes to parking money long term. So,for me hassle free.
What necessary action would that be? I haven't taken any action whatsoever and won't need to. If you're thinking about Personal Information (KYC), that's been taken care of by Customer service at my branch when I opened a new Fixed Deposit Account.
Does Krungthai have internet banking? If I'm using KBanks internet bank K BIZ, my daily limits are maybe 10 times higher than compared to the K Plus app.
I know people that were able to increase the withdrawal limit and transfer limit by visiting their KBank branch. It seems they check the account activity and also the amount you have in your account/s.