How to safely change Innodb variables

I’m using Maria DB, version 10.2.22, where one database column uses FULLTEXT for a broad document searching. However, I’ve ran into a "Table handler out of memory" on some searches. The table itself is only 4.4 GB. I’ve read on stackoverflow, that changing some of the InnoDB variables such as:

• innodb_buffer_pool_size

• innodb_ft_result_cache_limit

from their default value to say 4 GB could potential solve to the memory issue. My question is three parts, I suppose.

  1. Are there any other variables I should consider changing.

• innodb_buffer_pool_instances
• innodb_ft_cache_size
• innodb_ft_total_cache_size

  1. Because this DB is fairly critical to run, after running the command lines to change the variables would I need to stop and start the MariaDB service to fetch these changes?

  2. If, restarting MariaDB services is needed, can anyone point me to a guide as far as how to safely change these variables?