The question as written feels like a localized rant instead of a question with a generalized answer, but here goes:
TL;DR - Most of this is normal in the industry: adapt to it, or quit, are essentially your primary options. A few of the points you raised are legitimate concerns (accessibility, and lost productivity), but would need to be approached in a constructive manner to be taken seriously. Both have solutions, if you're willing to find them.
This is not a question of age, but, for the most part, of your apparent unwillingness to adapt to normal changes in your work environment.
Recently we've grown and become much more corporate-feeling, and changed our entire software infrastructure.
Normal in any company, but may signify a change in corporate culture resulting in it no longer being a fit for you.
We used to use Dropbox to share files, now we have to use Sharepoint.
Sharepoint's often down or files I upload disappear.
This is one of a few problems:
- Learning curve: You may need to actually take the time to learn to use the software properly
- Actual account/SharePoint instance issue: If you're positive it's not something you're doing wrong, this is a legitimate issue to raise with your SharePoint support team, or local helpdesk.
Either way, SharePoint is used by millions of people on a daily basis, and this is not a standard behavior of the software.
It's so much harder for me to use than Dropbox.
Your company as a whole has changed software strategy. This is normal corporate behavior, and not within your control. It's on you to adapt, not on your employer to adapt to you.
I was using the CS5 suite of Adobe software, and they upgraded me to the latest, and I lost a lot of features. I'm much much slower and can't work at the speed of thought, if that makes sense.
They also took away my Mac and gave me a Windows machine. I just can't work as well on it, it's so hard for me to navigate files or do basic tasks. This is especially bad for webdev stuff, Command Prompt isn't nearly as good as the Terminal was for running local web servers and other command line work.
These are both potentially legitimate concerns, because they have actual business impact. You can certainly raise these issues to your manager, but they need to be raised constructively. Most importantly, you need to be prepared for the answer to be we don't care, get used to our new deployment strategy. In that case, you may want to prepare constructive things that you could request (additional training, for example), and perhaps, an outline of the direct productivity impact, as measured by your workplace standard metrics ("this will take me X hours longer until I've learned this software").
The hardware issue may be easier to 'win' than the software one: older software is a security and maintenance issue (particularly if it's EOL), as well as a support issue.
They switched us from Gmail to Outlook. I can't figure out the UI, and it keeps changing anyway. It's so hard for me to do basic things like just sending an email.
Raising this as an issue is unlikely to reflect well on you: e-mail clients are not specialized software. Any reasonably competent manager would likely dismiss the argument that "Outlook is too hard to use, I want Gmail".
The UI's really hard on my eyes too.
Check into available accessibility changes that can be made in Windows/Outlook. This isn't normally a reason not to use the software (because solutions do exist for most issues), but is a legitimate and common concern.
I used to know all the keyboard shortcuts and now I don't.
So learn the new ones.
I got books and spend time at work trying to learn to use these new pieces of software
Get better books. Take auxiliary training courses. Do whatever you need to do.
but they just aren't as good.
Personal opinion - of no use when attempting to challenge a company-wide strategy.
I used to be able to work so well and now I can barely get anything
done. All the younger employees aren't having problems - I feel like
I'm being pushed out for my age.
This likely has absolutely nothing to do with age, and everything to do with personal change resistance on your part: changes in corporate software strategy are normal, and there are much easier ways to force someone out of a company, than to make every other employee learn a new program.