macOS · Research guidance. Instructions are based on publisher guidance; a UK IPTV account was not tested on this platform.
Start with the affected application
Apple documents automatic spelling correction and an app-level Edit menu control where supported. It also says some applications use their own spell checker. If an unwanted correction occurs in one app but not another, that difference is useful evidence; it should not be collapsed into a claim that every Mac keyboard preference is broken.
Keep the test comparable
Use the same harmless invented phrase in the affected app and another suitable text field. Note whether the difference appears immediately, after punctuation or after choosing a suggestion. Do not use private playlist credentials as the sample. A deliberate repeated input is easier to interpret than several unrelated sentences entered under different conditions.
Review the relevant controls
Inspect the app’s Spelling and Grammar or its documented own settings. Apple describes reverting an automatically corrected word and distinguishes inline predictions from correction. Preserve the assistance useful to the viewer and adjust only the relevant context for the comparison rather than clearing every dictionary, account and application preference at once.
Report the actual boundary
A support note can name the app, original input, resulting text and correction setting without exposing personal content. If the app has no documented control, report that limitation to its publisher. The absence of a familiar Edit menu item is not proof that a browser account, network connection or viewing service needs to be reset.
Questions, answered
Do all Mac apps necessarily use the same spelling controls?
No. Apple notes app-level controls and separate app spell checkers.
Should an exact text comparison contain private credentials?
No. Use a harmless representative phrase.