Take notes.
One of the best ways to remember things is to write them down. Take notes during lectures, (even if those lectures are online and recorded) because you will remember things you wrote down better than if you watched the lecture several times. It is the same for readings, be they primary sources, articles, or books; write down what you read in your own words, and you will remember it. There are several different methods for taking effective notes, easily available on Google. Find one that works for you. If you need to memorize dates, make a timeline, since it is far easier to remember dates in relation to each other than memorizing numbers separately.

However, keep in mind that very few university-level history courses will ask you to memorize a lot of information. If your courses are essay-based, then most of your work will be your own research, with reference materials easily at hand. Even in final exams, multiple choice questions about names, dates, and facts are rare, with some exceptions in first year courses. The most common questions in exams are essays, primary source analyses, and ID questions (an ID question will give you a name or event, and ask you to explain the significance of it). Only the ID questions require much memorization, and even then, there are rarely specific details you must give, and you should instead focus on connections to larger issues. In general, focus on large themes in your courses.

More specifically, see if your course syllabus has a section titled something like "learning expectations", usually beginning with a phrase like "In this course, students will learn..." This section often tells you what the professor hopes you will get out of a course, and sometimes will tell you the major themes the professor is going to cover. This can help guide your note taking, and gives you some clue to the questions that might be asked in exams. Also read the description of the course in the syllabus, for the same reason.

I hope this helps!